I would start by not setting your models to free! It hurts the industry for everyone else when people give away models and is no good for your pocket either.
Also, I would avoid modelling things that are copyrighted like StarWars, StarTrek, Disney etc. Most devs/ companies/ advertisers won't download them because of fear of copyright issues, no matter how good your models are.
Expand on your descriptions and offer more previews images as well mate. Info is a little lacking.
Good luck!