Use blender, it's free. If you can get a hold of it Maya do it. It is a great piece of software, one of the best actually and it's what I use, but it costs anywhere from 500 - 1000 dollars
Again it takes time, practice, and a lot of research. It took me two years of schooling and some contract work to get to my level now, and I bet MadMan1701, Warped9, and whoever else I forgot to mention, a LOT of man hours just practicing and learning to get to their level of expertise. They say it takes 10,000 hours to master something, I've only put in maybe a quarter of that number! (there are multiple disciplines: Modeling, Surfacing, Texturing, Lighting, Rendering, Rigging, Animation. Just to name a few.)
Also for tutorials Digital tutors, has a lot of good stuff for beginners, and the gnomon workshop for the more intense (read: cutting edge) stuff.