Many tight communities exist among Silo, Blender, zBrush, Messiah, MoI, Houdini (can't remember everyone) users, where you can get in and learn. I'd recommend finding some easy free tutorials for whichever software you attempt and stick with each project until you learn that lesson. Then go to the next lesson. Here's a good site to get some basic 3D understanding (the GuerrillaCG tutorials hosted on the creator of Silo's site) -
http://www.nevercenter.com/videos/tutorials/?vidclip=GuerrillaCGPolygon.mov The temptation is to think another package has something you don't have in your present package. To overcome that need to buy and buy lots of packages, you can guarantee the software package you have will not do everything and you can do whatever you do well by sticking with it.
Before you commit to one package, it might be better to go to their forums and ask questions or just listen to their conversations to see what they're like. Are they helpful? Friendly or feisty? Ask others who have various packages what they think. Try the demos one at a time (not all at once - too much info at once can constipate the brain).
One last thing to realize - eventually you will work out a pipeline of two or three (maybe more) packages from which you will forge your creations. This will take time, but you will someday probably have at least two, if not three or four, software packages that you string together to complete your work.
Good luck.
