Create an effective work portfolio and link to it from your resume.
For a creative industry such as copywriting, it’s not enough to tell clients about your previous work. They need to see your work for themselves to determine if your style or voice is aligned with their brand. So make sure you compile a portfolio of your most powerful and successful work and link to it on your resume (or submit it with your resume). Your portfolio should show the strength of your copywriting and the breadth of the variety of copies you can do.
LinkedIn is also a good place you can link to: just make sure your profile is up-to-date, and you're using good copywriting in places like your LinkedIn summary!