When people talk tell me how they found the project, they often cite the visual identity as something that makes it stand out. I have the benefit of coming from a graphic design background, so I put a lot of stock into things like the imagery used for announcement posts, as well as making UI elements feel distinct from what RenPy gives you by default.
I can't say I've gone in with much of a publicity plan (I've been happy to have this be something that people find through word of mouth), but I do think that developing a signature visual style has definitely helped to give the project more intrigue.