I'd also recommend Blender to a certain extent, given that it is free and has a lot of features. However, I'd start off by learning how the basics of poly modeling. I was looking for something by Bay Raitt but this is good https://www.youtube.com/watch?v=CpSAG85Rsk0 The most important aspect of the software is useability. You don't really need that many tools to be any good - having them just make things easier/quicker.