Dustin Said:

what should I include in a copywriting portfolio?

We Answered:

Compile all of your best writing samples. It doesn't matter if they were done as mock-ups in school. When I landed my first copywriting job, my portfolio was entirely composed of things I'd done in college. I'd recommend putting your work in a nice leather binder, with page protectors.
Definitely play up your experience as an account executive, especially your marketing presentation skills. Basically, sell yourself the way you'd sell any product you're writing about.
Good luck!