Great question, many entrepreneurs are stuck before launch because of this hurdle. I have helped many individuals turn full time entrepreneurs through succinct consecutive coaching in various industries. Here are my suggestions, but keep in mind they are generic because you didn't provide any details.

1. If you have a prototype or design, re-design it with the intentional focus of removing certain features. Making trade offs are critical and simplify your introduction, pitch, and value proposition as well increase the chances of people being 100% impressed with the limited featured offering rather than semi impressed and focus on what is done wrong.
2. aim for simplicity in your pitch, avoid jargon and create a simple story on how to present the problem solution your 1 or 2 features is offering. - go to older family members for this, not friends or coworkers.
3. go to Fiverr.com and maybe if needed look there for a cheap and quick prototype mockup.
4. create simple landing page to present as if you are a fully working startup. go to www.instapage.com for quick landing pages and if you want a domain go to www.unthinkhosting.com for cheap domains - use code unthink for discount, it should give you some savings there.
5. go to startup weekend events instead of all 3/4 above and just create a simple pitch (under 1 minute) to present your problem and solution idea. if selected you get a team for a full weekend to validate something together.
6. Or create a facebook product page, upload some images (not sales pitches) of problems w/ problem story descriptions... post a lot of those... randomly posting images of your product (already simplified in features) and launch a small budget campaign, say $15.00 for paid advertising featuring your simplified product image, little or not text in the image but with a very short story and solution as header.

trust me, is critical that you remove features. If you are not willing to make trade offs, from my experience you are not ready to try entrepreneurship at all.
I hope this helps and look forward to seeing you succeed!
Humberto Valle

I have developed and successfully sold many of my ideas in the last 15 years. There is a process i follow that gives me great results.

When validating an idea, You need as many opinions as possible from people with different backgrounds. It can't be answered by a single expert.

First you need to protect your idea (if possible) and a working prototype (depending on the product).

I agree that surveys are great to quickly evaluate interest.

Next step is to start a Crowdfunding campaign and see if people are actually willing to pay for it.

While collecting funds for developing you also collect ideas for improvement. Double win.

Give me a quick call so i can tell you the exact process i am taking every time i come up with new idea.

I've spent more than 20 years helping people understand their customer's needs, and it starts with listening and observing.

First, you either need to invest time or money...there is no other way. I would suggest time, and I would refer you to the Lean Startup methodology. I good online resource is leanstack.com, Ash Maurya's site.

If you have an idea you think might solve a problem for someone the first step is to validate that who you think has the problem actually does have the problem, and they have tried to solve it, have spent money trying to solve it, but still have the problem.

So identify potential customers and go talk to them about the area you are interested in. Don't pitch them a solution yet until you have validated the above hypothesis. Listen to what they say, watch what they do.

This is a starting point, so check out Lean Startup or Business Model Canvas.

If you want any additional details, give me a call

Consider running a survey with Google, this is one of the fastest ways to publicly validate a concept or direction: https://www.google.com/forms/about/

The best way to validate your product idea is to talk to your customers / users of your product. Don't pitch them your product directly, but rather try to highlight if the problem your product is solving is in fact perceived a problem by your users and what is that problem causing them currently. This will help you figure out if the problem is worth solving and if customers would be willing to pay to solve the problem. So don't start testing an idea, start with finding the problem.

I will leave it to experts and would start off by suggesting to watch a video on Idea Validation by @DanMartell the CEO of Clarity.fm http://youtu.be/gKDhDrSLp4E

Also here are few videos by Lean Startup Guru Eric Ries
https://youtu.be/hwlRxZJuWTY
http://youtu.be/fEvKo90qBns

Hope this help. You can always IM me and we can do a free call and I might be able advice or help validate your idea.

There are already a lot of great answers, including crowd-sourcing, a test web page, showing a prototype to your future consumers.

I'd like to take a step back and share the 3 coaching tips that I always give to startups (and which founders have found most useful).

Here are the 3 coaching tips :

1. Business is about serving people – Be very clear on which people you are going to serve.
This clarity will help you to define your brand’s tone of voice, your design and graphic world, your pricing, your go to market...

When I understand a startup’s target group is ‘human who breath’ - this happens often- I suggest more focus instead and the following framework:

- Define 2 or 3 target groups you could go after
- For each of these, define the issue your product will solve
- Test with first prototypes (of a product/service/website)
- Adjust and retest until you have 1 specific target group that your product can serve (i.e. solve one of their issues)
- Keep in mind the target group and benefit in everything you do (website, packaging, PR text, etc.)

2. Make sure your product is unique and your target group is ready to PAY for it:

o The unicity can include an innovative or superior product, a competitive price, an innovative go to market model. This will reduce the risk of your competitors piggy backing on your offer. It will also help you to write the story of your product and brand, which will increase your credibility in the market place.

o A target group ready to pay is a guarantee that your idea has potential to turn into a business. Unfortunately, free products to your friends and family won’t be representative of your chances of success in the market place.

3. Starting your business is different from anything else you’ve ever done - Stay humble:

o Start small and focus: many startups come to me with a proposition including multiple lines of products, planning a multi-channel distribution and a multi-social platform approach. Their unfocused approach spreads resources (time, money) in a moment where resources need to focus on increasing your conversion rate with your specific target group.

You can plan tests of course, but start with 1 preferred social network and 1 preferred distribution channel. Learn first, then expand.

o Get coaching in the areas you aren’t an expert: this will reduce the amount of mistakes you will make and maximize your chances of success. You can find mentors in network events or on expert platforms such as Clarity (you are already here, do schedule some calls to find yours :).

These 3 tips stay top line and are designed to get you started. Based on the above, the next step should be a business plan one pager including your target group definition, the issue you are solving, your product or service description and pricing, your distribution channel, and how you are planning to reach the target group. Once you’ve done this, you can start testing, and indeed many shared great tips on best ways to test.

A watch-out for those who currently are working in large corporations like I do: Counter-intuitively, we are among the ones most at risk of making mistakes. Read about mine in My 5 Mistakes As An Entrepreneur Coming From Corporate (www.linkedin.com/pulse/my-5-mistakes-entrepreneur-coming-from-corporate-serena-de-maio).

Good luck in transforming your ideas into business. Despite the difficult bits, the learning curve is steep and exhilarating, you will meet amazing passionate people and it is definitively worth it.

Validating your ideas is an important step in developing products that people want and will pay for.

Before validating a product idea, validate a need for a solution in your niche. Simply set up face to face interviews with people you believe are in need for your idea.

In the first phase of validation, don't talk about your product or present prototypes. I have an article with step-by-step instructions to guide you through the process and even a downloadable pdf with an interview questions template.

https://www.aireplastics.com/validate-product-ideas/

Use these answers to adjust you product idea to address the pain points of potential customers.

In phase two, you will present test your prototypes. Here's another step-by-step guide to doing this efficiently and correctly.

https://www.aireplastics.com/prototype-testing/

These interviews won't cost money but you will have to invest time. Any investment in time will save you 10x time and money in the future of your product.

Hi
First of all, the fact that you are talking about market validation is great. I've seen so many startups invest time and money, only to find that no ones wants/needs their product, or that they only want a certain aspect of it (whilst the startup spent money developing a whole bunch of other features), or that they aren't willing to pay the requested price. So you're already one step ahead.
Also, the sooner you validate your product, the better! That said, the version you are validating needs to be representative of the end product, or else the validation isn't reliable.
So, how should you validate it?
1. create a business model canvas (which is what all startups should start with before creating a business plan),
2. Setup a Wix or Wordpress website (this can be done for free / very low costs) or if your venture is a mobile app, you can create a responsive wordpress website that looks and feels like an app. On the website, include the price of the product/service, and enable people to order it (yes, even if it doesn't exist!). I am happy to explain how this can be done even though you don't yet have the final product and by still being fair to the people who click the "buy/order" button.
3. Spend a small amount (say $100 - depending on your budget) validating the idea (promoting the product/service that you listed in the previous stage).
This way, after only spending a very small amount, you will be able to know (if you did it right):
a. Do people like your product.
b. Do people want/need your product (not the same as 'a').
c. Are people willing to pay for your product? (this being the most important stage)
d. How much are they willing to pay? (you can check this by having 2-3 landing pages with different prices on each).
2 additional important points:
a) in order to rule out external factors like an unattractive landing page or advertising campaign, and assuming you have the time, create multiple landing pages / advertising campaigns, with different designs.
b) during the above process, don't forget to check how much it costs you to get each user/customer to click the "buy" button. If for example each click on your promotion/advertisement costs you $2, and only every 10 people who click go on to the "buy" page, that means each sale is costing you $20. Then check what your average profit per sale is, and then you'll know if your service/product is worth pursuing (obviously there are additional factors like return customers, referrals etc, but you will get a good estimated/validation of the idea/business).
I'm happy to help you with this matter further, as this is a critical stage which if done right can save you a lot of time and money. It would be best to have a call (regardless if with me or someone else), only after you've created a draft survey and/or the above landing pages.
Best of luck!