This is funny to admit but I often get confused with the spelling of some common words like vacuum (vaccuum, vaccum), accommodation (accomodation), customer (costumer), and many more! hahaha
I usually write them out and see if they look weird or not and that's how I determine which is right. Lol
Check out this link for the common mistakes. https://www.learnenglish.de/spelling/commonspellingmistakes.html
What are your lists?