Start with the people who already know and trust you. Most partners get their first clients not from ads, but from their existing audience, current clients, email list, social following, and word of mouth. Before spending a dollar on advertising, tell the people already in your world what you now offer and how it helps them.
A simple first sequence:
Announce it to your existing clients and email list.
Post about it on the social platforms you already use.
Add a clear section to your website linking to your storefront.
Ask happy clients to refer people they know.
Marketing gets more advanced from there (paid ads, funnels, and so on), but the fundamentals are the same: be clear about who you help and what problem you solve, and make it easy for them to take the next step. You don't need to be everywhere, you need to be clear and consistent in one or two places.