The worst motivation for starting a business is the need for income. A business has to be built over time based on meeting a market need. Of course a business must make money to be successful, but this can take a bit of time.

So, the real need is to use the online world to make money. Based on your copywriter skills, here are some ideas to get you started:

1) Start a blog. You can do this for free with platforms such as Blogger and WordPress. This will provide you a chance to show case your writing talent. Writing articles about copywriting can both demonstrate your writing ability and be used to market your approach.

2) Join job markets. There are several freelance sites you can use to make extra money without little to no cost, such as Upwork and elance. You will find jobs on these that will help you earn money and build your portfolio. The pay can be low as the markets tend to be aggressive but a few good contacts can lead to a better source of work.

3) Build your network. Connect with people who provide web marketing services. They need guest bloggers, ghost writers and ad copywriters. Over time you can build a steady source of freelance work.

Once you have a good portfolio and practice, you should consider building a branded web site. But first, build your freelance brand. This approach works with other skills too.

Let me know how else I can help.

I have hired many copywriters over the years...

Your best bet with your skills is to write some killer sales copy for your own copywriting service and promote on Warrior Forum as WSO, and actively engage other agencies and marketers in related forums, subreddits, etc... Post an offer on reddit.com/r/forhire
Just promote yourself as a copywriter... Once you have a basic income coming in you can start finding ways to scale your expertise. (i.e. finding a whitelabel or drop ship provider and list those items as new items on amazon and write better sales copy for your listings.

Shoemoney, one of the best at making money online started off with Ebay arbitrage where we found price discrepencies on electronis on ebay from country to country, bought a cheap item, relisted it as a much better listing with a higher price and sold it before he ever paid for the one he was buying.

A less risky version would be to visit slickdeals and fatwallet. Buy great deals, and list them on craiglist locally for sale. People on craigslist wont really comparison shop and they will assume its cheaper on craigslist than from a store.

IF you need to make real money to support a family... You can find lots of work from home jobs like being a usertester for usertesting.com , writing on textbroker.com copypress.com and the many other writer marketplaces. Post gigs on fiverr. etc... None of these will make you rich, but it will make you a living. Drive from Uber on the weekends, become a task rabbit worker, etc... lots of ways to find work online for offline odd jobs...

Good Luck.

Don't start. Asking "where do I start?" is a bad sign when your only goal is to make money.

There's nothing wrong with making money, of course. But any project must solve a problem or create something of value. Right now you haven't identified anything to do worth doing.

A startup isn't going to succeed unless the person founding it knows what he's starting and why. Wanting money may be your justification, but why would any customer care about that?

Continue working in areas where your work is valued. If possible, convert those jobs as an employee or freelancer into your own ongoing client base. Later you can build a brand for yourself around that ... as your actual business grows.