Statistics have a cascading effect. As you increase the Small Preview count, the count will also increase for Full Previews, Shopping Cart additions, and Sales because users will be seeing your products more. You will have to experiment and see your results, but below are some possible ways to improve your results on TurboSquid:
Small Previews: Add keywords and fill out all of the technical description fields (to show up in advanced searches on things like polygon count).
Full Previews: Edit the small thumbnail to better display your product. Because of the size of the thumbnail, you might want to display a close up of a smaller part of your product.
Shopping Cart: If your product is has many Full Previews, but fewer Shopping Cart additions, you might want to try to increase the quality and quantity of the thumbnails and technical description.
The date range of the statistics can be limited to examine time periods more closely and watch how changes affect activity.
Sorting by several fields allows for further flexibility on analysis.