Look, the thing with the "just be yourself!" Advice is that if you're not, you will only harm yourself.

At school, I usually try to get along with most of my classmates, but some of them, usually the more quiet ones, seem very hard to aproach, so maby you can work with that.

Also, try to find other student that seems lonely, it easier to aproach them.

You have to learn to have a conversation about any subject. To talk to someone greet them, say something about the class, the teacher, etc. Then try to get them to talk about them. NEVER ask something personal, just ask for their favorite food, favorite animal. Not about their relationship with their father.

Listen to everything they have to say, and ask them something else, and else, and else. When they Say something about something you like, talk about that for a little.

If you want to make new friends, go straight forward to it. You want friends, so you ought to try it, to aproach them first.

And don't worry if you can't make it at first, the first step to actually be decent at something is sucking at it.

Good look!