Bin Chen has an interesting post on making Emacs use as efficient as possible. The idea is to remap the commands you use the most to easy key sequences. To do that, you need to know what commands you’re using, of course. As usual, Emacs has us covered. You can count the commands you use with keyfreq-mode. It’s easy to set up—see Chen’s post—and you can even exclude commands that have key sequences you like.
Xah Lee has done similar research here and here and even gives some advice on which key sequences are the most efficient. If you’re into remapping keys for maximal efficiency you should read all three posts.