Sounds like art/3D modeling is what you're into. Consider starting with Blender, which is free, opensource, and unrestricted on what you use it for. While the other programs you listed are more powerful and you might make a case that they are better for certain tasks (I'm not an artist, so don't take my word for it) I have heard that the basic skills required to use one 3D modelling program translate well to others. Anyway, it's free, so you might pick that up and play with it.
If I wanted art to be my own road into the world of making games, here's what I (and perhaps you) might do:
- Use Blender almost every night to make something, trying to make something new, using a new feature combination each week.
- Practice and learn to draw and sketch. I'd keep a notebook in which I'd force myself to fill a page each night, drawing *something* to teach my brain to always be thinking about how to fill spaces and, whatever else, I don't know. (I took a painting class and my art professor was very insistent on filling a page in a sketchbook each night, and it seemed to help with idea generation insofar as visuals. It's the same thing for writers and journals, musicians and jamming, etc.)
- I'd try to go to school for an art degree, at least an undergrad, to learn fundamentals. I would definitely take sculpting (with real physical clay) and 3D modeling (computers) courses. It'd be a good idea to take a lot of diverse extracurricular courses (histories, a language, sociology courses, psychology, sciences) to round myself out.
- I'd travel as much as i can afford to, maybe studying abroad in a student exchange program. I'd shoot for at least two very different countries before graduating.
- Get out there and live. The more life experience you have, the more you'll have to draw on for your creations.
With that formidable, probably four to six year education plan, I'd have a lot to do. That would give me a way to build up a portfolio and start applying to various studios. Here are the monsters and heroes and scenes and structures and whatever else I have rendered in 3D: photos of my sculpts and screep caps and wire meshes of my models in Blender/3DSMax/whatever.
You have a long but very fun road ahead of you. <3 Good luck.
EDIT: I see this was just moved from Game Design (where I saw it) to Visual Arts...where you'll get opinions from people who are far more versed in art than I. I hope some of this was helpful, nonetheless.