<p>The key is to say the right things to the right people. If you get an A on a test, it's fine to share it with your friend who happens to be valedictorian of your class. It's not fine to share it with a friend who is struggling with her schoolwork. Think before you speak and consider how what you say might be interpreted by others and you'll be fine.</p>
<p>you probably shouldn't do other people's homework if the both of you want to stay in school.</p>
<p>As far as grades, you can simply follow this rule: do not talk about grades unless you are asked directly by the other person, and don't talk about them in groups. ("How is X class going?" does not mean you respond with "well I got 3 A's so far". How bout, "it's kinda rough sometimes, but I'm doing pretty well I think")</p>