Look up the spelling of words you habitually misspell and check if you are doubtful. Be alert to possible problems in agreement or the placement of modifiers; be sure every pronoun has a clear reference. See that your punctuation is both correct and appropriate.

Remember that you can spoil an otherwise good piece of writing by a blatant, distracting error. Since it is very difficult to see your own errors, don't be afraid to have someone else read the piece over, looking specifically for errors in spelling, punctuation, and grammar.