This is a list we could all make good use of. Yourdictionary.com has compiled one list it calls the 100 Most Often Mispelled Misspelled Words in English, and a second one, 150 More Often mispelled Misspelled Words in English, and there are a lot of common words on both of them.
Just doing a cursory skim of the lists, I already see a few that always make me have to stop and think. Yes, “accommodate” does have two c’s as well as two m’s. I don’t have much occasion to use “bellwether,” but if I ever do, I’m quite likely to misspell it “bellweather,” as so many others do. And I misspelled “daiquiri” literally for years. Didn’t dampen my enthusiasm for the drink, though, thank goodness.
After years of not remembering, the only way I could finally remind myself how to spell “occasionally” was to make up a personal mnemonic: “The external consonants are doubled, the internal ones are not.”
Each of us has our own set of words that simply will not stick no matter what we do. We can’t give up trying to spell them correctly, though, even if we’ve got an unfortunate bug in our mental programming. We either have to create mnemonics to help us remember (I learned how to spell “parallel” because someone gave me the mnemonic, “The two l’s inside ‘parallel’ are parallel.”), or we’d better keep an online or hard copy dictionary handy.