Others have given good advice; in particular, the idea of using a cheat sheet. People have made nice ones, but it's easy to make your own. It should show how to do the things you're already doing in your current editor. Other than that, the "trick" is just to commit yourself to using your chosen new editor all the time (except for emergencies).

If you don't already touch-type, learn that first. You should have a diagram of the keyboard (or at least the hard-to-remember parts). When you forget where a key is, look at the diagram not the keyboard.

If you choose Vim, feel free to PM me if you can't figure out how to do something in it.