Basic “whom” use shouldn’t pose too many challenges. If you can remember to think of “who” as the cousin of “I,” “he,” “she,” and “they” (the thing doing the thing, a.k.a. a subject) and to think of “whom” as the cousin of “me,” “him,” “her,” and “them” (the thing being done to, a.k.a. an object), you’re most of the way there.
