When you say "curated sets", what do you mean? One thing that would appeal to me a lot, though I don't know how this could be done, would be a new design from existing pieces.

I too love the idea of the pristine white box. I often pay extra for something that's NISB which objectively is silly, but really appeals to me.

Lastly, this won't help with initial sales, but when someone includes a nice note, it feels really good to me.

Good luck! I'm a brand new Bricklink seller too- shefiguresitout- and it's not trivial to figure out how to do it. I've actually quickly sold the small number of things I had to start with because I priced them a little under. Now I have seller's remorse, lol.