The key with stock photography is that it requires real work - not just posting your existing photos. You need to be able to create images that stand out - using software, compositing, or simply making great photos. Often the images that sell are of common things - a bluebird rather than a rarity. You need to decide on your niche - what kind of images are you going to make that will stand out? Maybe it's food, maybe it's travel, or it might be something else. Build portfolios of solid images that help tell stories. Keywording is very important in stock photography because people need to be able to locate your image. The keywords need to include the obvious descriptive terms, but also emotional terms that align with buyer needs. All work needs releases as appropriate - people, property, intellectual capital, etc. As a result most stock photos involve models if people are included.
Don't expect meaningful results by just uploading images to a site. Expect your return to be commensurate with your time and effort toward stock - not including making the photos.