Paid traffic via Google AdWords will be your quickest/easiest option. Setup a couple of campaigns around highly-relevant and low-cost keywords. Target KW's that are very specific and you'll get them for less cost-per-click. (CPC)

You can turn the funnel off as soon as you get enough users for testing purposes.

I like to use all or some of the following
1) Get some press on niche blog / news outlet / industry publication
2) Leverage my personal network
3) Facebook Ads - cheap CPC but not as qualified
4) Sponsor a podcast that's relevant with big audience
5) Create great content and attract the users for free

Those are the top 5, everything else is just another paid channel.

That being said, Twitter Ads are cheap and they have a new lead gen tool that could work for you = more cost effective than Adwords.

Facebook marketing would also be a fast way to get you traffic -- and it is especially targeted. You can aim at a competitor's page on Facebook and only message to their followers. Should be a fast/easy way to get traffic to your site.

BTW, if all you need to (50) people per day, why not message out on social media? You can't control the traffic once it get's going. It's a double-edged sword. :-)

Also: Quora, Clarity, Angel List, LinkedIn Groups, Stack Overflow, etc... (Those are all free to engage!)

1. Ask for testers on twitter
2. stumbleUpon - always drives traffic
3. Put an ad up on craigslist
4. Send email invites to friends and tell them to pass it on for people to beta test something exciting
5. Post to inbound.org

First I believe you need to think about what kind of visitors you want to attract and why.

You also need to know why they'd like to visit your website. What are you offering that they'd like to see?

Then you can think about the strategy.

You might try Google Adwords, Facebook ads or LinkedIn to reach your audience.

Also if you need 50 users per day one of the best things you can do is to invest in content marketing. Let's say: if you blog daily and share it on social media and bookmarketing sites it will be really easy for you to get 50 visitors per day. Your content will also rank in search engines and will bring you organic traffic.

If you need more insight on how to bring traffic to your website, feel free to schedule a call. I'd love to help you out.

Best regards,
Martin Zhel

This depends on what you are doing. Let's start with some caveats:
1) Speed is important - you don't want to spend a lot of time screwing around, you just need some traffic
2) Money is important - you would rather have some people on the cheap than a very well qualified audience that you paid more for.
3) You are pretty early - you don't have some massive social media following and stuff like that. Frankly, if you had that you would already be getting 50 users per day.

Assuming these caveats are true, people suggesting things like Google/social media/etc. are probably heading you in the wrong direction. You probably don't want to spend days and days hunting around Google for pockets of low CPC keywords that have enough volume to get you the traffic you need. You probably want to just dial it up, set it and forget it.

If #2 is not true, then Google Adwords is solid. You will pay a pretty high CPC, but you will get a very well qualified, bottom-of-the-funnel kind of audience.

If both caveats are true, I would concur with other people that mention Facebook. Big audience + Low CPCs = easy to get 50 people per day.

Things like "advertise on some podcast", "start a blog" or "get some press" seem like advertising mechanisms where you cannot control the amount of traffic you generate on any given day, may be below your target or above your max, result in spikey traffic, and may take a long time to actually get started. I wouldn't do that for testing.

Now, I have no idea what you are doing, so the true, true answer may have some variability based on that, but these general guidelines are pretty good.

If you are strapped for cash and really just trying to generate eyeballs, head over to Canva and make an infograph. You can easily create a really visually appealing & informative piece around your niche.
From there I would submit it to all the infograph databases, I'd then tweet it out or privately tell other leaders in your industry. A lot of times they'll link out to just cool stuff!
Lastly, you could jump on technorati or something similar and compile a list of all the blogs in your nice. You could contact each and ask to guest blog or tell them about your infograph.
One day of hard concentrated effort would do the trick!