I know I nag a lot about what the author’s job entails. If you’re fortunate enough to have a conventional publisher who provides a cadre of competent editors, then you may have the luxury of simply putting your story down for them to clean up, much as your mother may have done your laundry or cleaned up your room when you were a child.
However, if you’re an independent author, you need to be aware that proper grammar, word usage, punctuation, and so forth is YOUR JOB. Even if you hire an editor, unless you understand there are several types of editors, your work may not be at its best when it goes to press.
One thing that occurs frequently is misuse of homonyms. These are words that sound the same, yet have entirely different meanings. You can find a great list of common offenders as well as words that are often confused on Grammarly here.
Some of my pet peeves are shutter (those louvered, wooden panels you see on windows) versus shudder, which is to shake or tremble; Hanger (what you put your clothes on in the closet) versus hangar, (a building for aircraft storage); their (possessive pronouns for they) versus there (place) versus they’re (contraction for they are); lead (a type of metal or the graphite in a pencil) versus led (past of the verb to lead); whose (possessive pronoun) versus who’s (contraction for who is).
Check out the list on Grammarly. If those terms aren’t firmly implanted in your brain, bookmark the page for future reference.