"Whatever you can do, or dream you can, begin it.
Boldness has genius, power and magic in it." -- Goethe
Rule 0: You gotta have fun!
If you don't have fun you won't get very far and you won't enjoy getting there. It is easy to turn photography into work (hard to turn it into a job) if you forget to have fun.
Rule 1: Make, not Take
Previsualize how you want the photo to look after all the post-processing has been done on it. Get in the habit of checking all edges and corners before clicking the shutter. Try to go closer if you can, since it often makes a better photo.
Rule 2: There are no Rules
There are only good photos. If you can make a good photo by breaking a "photo rule", then break it and make it! Even if that means grabbing a photo on the run without thinking about it, if you have to.
The Best Way to Learn Photography
The best way is to reshoot and repeat. But don't forget Rule 0! Milk a project dry while you are having fun, and then move on. Also, you can come back to old projects when they become fun again.
Here's how it works:
1. Make a photo
2. Evaluate it ASAP, chimping if possible.
3. If you can see how to improve it, go to step 1 and re-make it.
4. If you need help, ask some friends or post in an online forum. Then remake it in step 1 again.
5. If you are still not satisfied and aren't getting the help you need, set it aside and come back to it days or months from now.
Remember, if it's not fun, make some different photos or do something else.
When I was in my early teens, I got a Polaroid Big Swinger camera. Being a Polaroid, it gave near instant feedback compared to ordinary cameras. Never mind that it had only one control (lighter/darker) and only one film and only one print size: I learned more about photography with that camera than with any other until I got my first DSLR.