cartooning

For a hobby all of them can be promising depending on what you put into it. Realize however if you haven't done anything like this before you can't expect to just pick up some materials and do killer with it. It's going to take time.

My advice would be to take up drawing first. With drawing, you can learn composition, detail, symetry, and work on problem areas you have before you spend a ton of money on supplies. Pick up a cheap sketch pad and get the feel for it. Once you feel ok with what you're doing then try something else.

There are a lot of books that can help you on your way as well. If you go this route check out as many as you can to see if they have what you are looking for.

The biggest advice I can give you if you're just starting is you need to really look at things and draw them the way they are not how you think they are. Really study what's there and see it not just look at it. Your brain will try to trick you and put out what it thinks it knows not what is actually there. When something won't look right to you thats usually whats happening. Your brain associates things to simple shapes and instead of drawing what you want your brain will throw out a simplified version of it. Retrain your brain!

Patience is also something you will need. You won't just be able to whip out the Mona Lisa after a week. It's takes time and dedication to get good. Even if it's just a hobby I'm sure you'll want to be good at it or why bother.

Hope this helps
Good luck