anything to distnguish differences between affect and effecta while and a while,sometime and some time and all the other words simular, in usage.
usage - Writeacher, Friday, April 11, 2008 at 8:16pm
Here's a webpage that has some really good explanations and examples.
Listen closely to pronunciations, too, whenever it's given.
Another thing to do is to look up these words at http://www.answers.com whenever you're questioning one or more.