If you aren’t sure if you really like a seller or not but are interested in them, check out their demos for sure. In voice acting those really help and give you a good idea. If you have a specific voice you are looking for, ask for a custom demo of what your script is. In my case as a voice actor, I really don’t mind doing a short little demo to give you an idea of what kind of voice I can do. I also like talking it over to make sure I get you the right voice for the job. I’ve was able to do that with a few projects and they’ve turned out to be some of my favorite ones I’ve done! So don’t forget to talk and communicate with your seller!
I agree with this @barrelofmonkeys , just ask us, a good seller is there to help.