Try to limit swearing, but don't keep on everyone's back about it.
(Yes, guys respect it if you don't swear, but not if you nag and bicker when other people do).
When a guy is sad, approach him and ask what is wrong.
If he ignores you or makes it seem like you're bothering him, just say sorry and walk away.
Try to make a point in a conversation, don't just make a random bunch of words to keep people amused.
(Even confront people about serious beliefs they have, and have a really good argument to back yourself).
A huge mistake many girls make is doing random/silly things like poking a guy or following him to look cute and funny.
It's neither. Guys will just be irritated! If you ever notice when a guy tries to impress a girl, it's usually the one who is doing something on her own she likes to do, like practicing a dance, texting to a friend, or even just playing a game. Anytime, where you are not prying for his attention and looking like you're doing something fun or important, he will appreciate you a lot more than if you are jumping on his back! You will also look more approachable
this way, especially if you're smiling cheerfully!
Try not to act clumsy, foolish, etc.
Try to be smart about what you do, because guys do not care for dumb girls.