1- It's okay to say how you feel, what you truly feel, even if the result isn't what you expected.
2-Never chase anyone and/or force yourself to make them notice you. If they want and are interested in you and what you're saying, they will listen to you, not ignore you.
3- If you don't like the way your friends are treating you and you don't want to tell them, you can walk away from them for a while. Or just tell them how you feel.
4- You can say "no" and don't have to explain why.
5- If you tell someone something because you thought you could trust them and then you find out someone else knows about it, don't freak out. Just breath and say "I don't care" because eventually: people will forget about it, you can't do anything about it and you have more important things to worry about.
6- It's completely fine if you don't want to talk to anyone about what's happening to you.
7- Sometimes, crying, makes you feel a lot way better.
8- If you don't want to go out, then don't. Staying at home sometimes is good.
9- Reading a lot can keep your mind busy and you don't think about what's making you sad.
10- Your heart can actually ache for someone/something and most of the time you can't do anything about it.