First you want to find out if you will even be interested in 3D art and want to get some practice so you can have a good solid foundation before putting any money into it. What you should do is download blender.
Blender
is free open source software that is fairly good for practicing your modeling. The layout is a bit messy and as far as animation and texturing practice you won’t get much out of it. For modeling, it is great. You get good practice learning various tools and moving points around to achieve the object you want to create.

The next step is to learn how to use the program and how to model things in general. To do this you can either go to school to learn or buy DVDs. But if you do not wish to put any money into 3d school then you can just use free video tutorials online. These are so great and it is what I have used. For the blender program specifically there are plenty of tutorials on the webpage, and you can find loads more from
Google
or
YouTube.

After learning about blender and gaining the ability to make objects, then you need to start playing around and creating things that come from your mind and not a tutorial. You’ll never learn how to do things you want to do without trying. There isn’t a tutorial for everything. So at this point find some objects you think would be cool to have modeled and make them.

Now that you have some skills is creating 3D art and you want to continue then you need to find the professional program you want to buy. My personal favorite is
Maxon’s
Cinema 4D. The interface is really nice and easy to use and you can make things in it as good as any other 3D art programs, But if you wish to check out others then look at Maya or 3DS Max.

So, how do you know which one is best for you? Well most of these programs have free trials or demos. Download this as get familiar with the program and see if you like it before buying. Play around with the different tools and features that that program offers. If you buy the program then you can start saving scene files and rendering beautiful images or animation.

At this point you can either quit and just keep your skill as a hobby or get a job as a 3D modeler, texture maker, animator, or the three together. Either way, how will you get your modelers seen? First of all and best of all you can join a forum for your program. For example for Cinema 4D, the absolute best forum site is the
C4D Cafe. At this site and many others like it, you can post what you’ve made, ask questions, watch more tutorials for more specific tools or functions, and just hang out and meet new people. On top for this if you want to make this your career then you’ve got a great way to advertise your skills. The other thing you can do is make your own website and host your objects there. This can get you known as well.

I wish you best of luck in getting into the 3D world. I hope you find your way there and have a lot of fun while doing it. 3D isn’t only for jobs and money, but it can now be a great hobby. So start modeling and good luck!