In my post on showing unfinished keybindings early, commenter hmelman points out which-key which is a package that give you pop-up help for partially completed keystrokes. Simply install the package from MELPA and add
to your emacs config file. Now type a prefix key like
C-x and wait one second (this delay can be customised) and a new window will open with a summary of the possible completions for that prefix. There are some nice screenshots at the project web page so look at those to get the idea.
This is a great way to remind yourself of commands or discover new ones. For example try
C-x 8 and wait to see what pops up – I’m sure you’ll find some commands under that prefix that you didn’t know about!