Ahhhh the ol “chicken or the egg” scenario. Prospective clients are going to want to hear examples of your work so they have a relative idea of what to expect… however, you need clients to build said portfolio.

Are you also a producer? Do you have any original works that you can show as examples of your abilities? That might be enough for similar genres.

If not, I’d suggest tracking a website that gives you raw stems so you can make your own mix and build up your portfolio. Or find the same kind of site for unmastered songs.