In vim, don't use the escape key to go back to normal mode!

No, don't, it really sucks, it makes you move your left hand way too much! Who decided to put this stupid escape key all the way over there anyways? Why aren't all the keys right under my fingers anyways? Who designed the keyboards? Ok, that's enough ranting for today.
So, you don't want to move your left hand to much and you don't have an über stretchable pinky finger to reach that key? Then you'll be glad to learn that you can use Ctrl-[ instead. From vim's help (see :h i_CTRL-[), you'll learn that

<Esc> or CTRL-[
End insert or Replace mode, go back to Normal mode. Finish abbreviation.
Note: If your <Esc> key is hard to hit on your keyboard, train yourself to use CTRL-[.

All right, it's all written there! This just makes me wonder why, when we first learn to use vim, we learn it's the escape key that makes you go back to normal mode... Now you'll be more efficient using vim!
Oh, you can keep on reading :h insert.txt while you're at it!
In fact, it's probably a better idea altogether to remap the stupid CapsLock key to the Escape key in your window manager and use it in vim. It's so comfortable to have this under your left pinky finger!
Another possibility (which is probably better since it's the one I'm using) is to use your window manager to remap your caps lock key to the escape key (but this doesn't work in tty's, so it's good to learn to use Ctrl-[ anyway).

Cheers!