I agree with Timitek. This is not a good business to look for "fast cash". This business really takes a long time to become established. Even if you have some great, well designed, and excellent quality models, if no one sees them then they won't sell. You need to really love this business, love 3d modeling, and take the time to create a lot of models for your portfolio. It helps if you have a large social media following related to your art.