I talk big because I like making monumental generalizations from obscure ideas. My proofreading's superiority claim has been backed up in the May, 1987 issue of "Gross Generalizations" magazine. I wrote a letter to the editor thanking them, but they never printed it. On to the meat of the post.
Assuming you have just written or edited some copy - read it word for word forward twice. Once out loud helps. This gives you a chance to test the flow, grammar and syntax. Next, read it backwards, one word at a time. Out of context, misspellings stand out, making them easy to correct prior to publication. While this deprives readers of that smug sense of superiority they get catching you in a typo, it gives you the warm glow of keeping your act together and depriving them of that satisfaction. Let them read this and get their own typo fix.
Many people rely on spell check. But it can't differentiate words with two spellings and divergent meanings. So if your typo happens to be a real word, you REALLY look foolish to savvy readers. To not-so-savvy readers, you leave them scratching their heads.