Learn how to write persuasively. You can learn this by studying others who've done it.

• 20 copywriting books you need on your shelf
• How to write copy
• The 6-part outline every good sales page has in common
• The Ultimate Guide to Remarkable Content

Practice writing, and build your portfolio.

• Write the copy for your newly-formed copywriting business.
• Offer to write for your friends or family if they have small businesses that need copy.
• Offer your copywriting services on sites like Upwork and Fiverr. 
• Write a pitch email to your dream client.

When you have done some writing practice, you can get a feel for the niche you want to pursue. 

Pick a role you want to own.

• Emails / Sales funnels
• Social media / Community management
• Search engine optimization (SEO)
• Digital advertising (PPC)
• Blog posts / Articles
• Video / Podcast scripts

To find your target market, ask yourself:

• What industry are your prospective clients in?
• What are their services?
• How do they use copy currently?

For example:

• Email funnel copywriter for SaaS companies
• Social media manager for nonprofits
• Blog posts for personal finance websites.

Finding your first client may be somewhat tricky, but once you find your first few clients, they're likely to refer you to their network.

Go where your clients spend time online, such as message boards, forums, and websites your client might frequent.

• Are you a writer for a niche industry? Start answering questions on Quora regarding your niche.
• If you're a video editor, find online groups for bloggers wanting to expand their content media.

Consistently provide value at these places to develop a steady reputation.

There are four main pricing models:

• An hourly rate is ideal for the beginner. It prevents clients from piling on work without paying you and help the client to mitigate their risk.
• By project. You'll know exactly what you're getting paid with concrete deliverables.
• By retainer. Your client will pay you a set amount monthly.
• Commission/bonus. This model can work in conjunction with the other ones. For example, your client promise an added amount for attaining X amount of leads.

• Focus on the reader. Great copywriters write about what their readers care about.
• Focus on learning more. Good copywriters invest in themselves. They read books on copywriting and marketing. They invest in courses and read other copywriters' stuff to stay in the loop.
• Be humble. Good copywriters are always looking for feedback as it can improve their writing.
• Use simple words and stories that read the way people talk when they feel relaxed.
• Write to your reader. Don't use "my" and "I" Instead, use "you".
• Use specifics to bring your writing to life.