My favorite proofreading tip is to have the computer read writing back to me. The computer won't skim over sections. It will explicitly read every word. Your ears will pick up things that your eyes won’t. Grammar issues such as messed-up tenses become super-obvious when you do this. Obviously this doesn't always help with misspellings and it rarely helps with punctuation.
(FYI, on a Mac it is easy to setup a key command to read back selected text in System Preferences > Dictation & Speech > Text to Speech)
(FYI, on a Mac it is easy to setup a key command to read back selected text in System Preferences > Dictation & Speech > Text to Speech)