re: What words do you always misspell even though they are simple?

Not really a spelling issue, but a "which to use" issue. Affect vs effect. I use "affect" when it is in a passive manner, such as something affecting me emotionally. I use "effect" when it is aggressive, such as the foul effected his shot (basketball). I think I am correct, but I actually don't know. And every time I use one of the words I feel as though I am guessing and I wait to get called out on it.