RULES OF THUMB

USING WHO OF WHOM

If you can answer the question being asked with him, then use whom, and it's easy to remember because they both end with m. For example, if you're trying to ask, "Who (or whom) do you love?" The answer would be "I love him." Him ends with an m, so you know to use whom. But if you are trying to ask, "Who (or whom) stepped on Squiggly?" the answer would be "He stepped on Squiggly." There's no m, so you know to use who. So that's the quick and dirty trick: if you can't remember that you use whom when you are referring to the object of the sentence, just remember that him equals whom.
Joseph Bauer, Master Carpenter, Indian Hills, Ohio, USA