The way for anyone to proof their own work for spelling errors is to read it backwards. Yes, from the end to the beginning. That way, you are not focused on meaning, but you actually see the word structure. This worked 99% of the time when I was teaching.
Editing grammar/syntax, etc can be done by the writer, but you have to read your work out loud to yourself. It's not a quick process, but again, it works almost all of the time.