Please do Your and You're, Who and Whom, Here and Hear. Those are a few that drive me nuts!
Your is always possessive. If the word is NOT designed to show ownership of something, "your" is the wrong choice.
You're is always a contraction of the words "you are." If you remove "you're" from the sentence and replace it with "you are," it should still make perfect sense.
Second: who / whom:
I must be honest. I still do not have total mastery of these two words and their usage. Most of the time, I can get them right. Other times, I can't decide which to use, and I wind up changing the sentence to eliminate the need to use the word. As a general rule, though, "who" is the subjective form of the pronoun, while "whom" is the objective. In other words, "who" would be used as the subject of a sentence, while "whom" would be used as the object.
Best example I know: "Who did what to whom?"
"Who" is the subject, and "whom" is the object.
Third: here / hear.
If your word has nothing to do with sound or the sense of hearing, then "hear" is not your word. That is the basic test. Still, on this one, I must admit a single weakness in usage. When I hear someone say, "Here, here" as a gesture of agreement to the comments of another, I don't know which to use.