One of the most useful and underrated things you can do to be more efficient with your computer is to learn keyboard shortcuts. Some of the ones I use regularly include Copy, Cut, and Paste with CMD+C, CMD+X, and CMD+V respectively. CMD+Z is undo in almost every application. I also have keyboard shortcuts I have mapped to easily add information to programs like OmniFocus and Fantastical. The number of shortcuts can seem overwhelming at first so I recommend trying and learning a few at a time. Apple has a useful list of shortcuts.