The thought of talking to your crush can be terrifying. However, you're never going to end up in a relationship with him if you don't work up the courage to approach him. That's why you need to banish certain thoughts about how you're not good enough for him. It'll be easier to start up a conversation if you stop worrying about these things when you see your crush:
You're always going to find a pimple or a hair out of place, which is why you can't use it as an excuse to stay far away from you crush. He isn't going to expect you to look perfect, so you shouldn't hesitate to walk right up to him and start a conversation. If he's a decent dude, then he won't care about what you look like. If he does, then you don't want to date him, anyway.
It sounds like a stupid idea to walk up to someone when you have no clue what to say to them, but you should do it anyway. "Hello" is a great opener, and if you're lucky, your crush will have something to say to keep the conversation going. Even if he doesn't, you can settle for asking him about his day or for asking for help finding a certain building on your campus. Saying something silly is better than saying nothing at all.
You can't let the fear of rejection stop you from going after what you want. Your crush isn't automatically going to know that you like him, just because you started a conversation with him. Even if he does realize it and reject you, at least you'll know where he stands. It's better to know for sure than to question his affection for months.
If the conversation with your crush lasts for a long time, don't become paranoid over whether he wants you to leave him alone already. People are pretty good at coming up with excuses to get out of situations they don't want to be in, so if your crush hated talking to you, he'd already be walking away.
For now, you should be focusing on having a regular conversation with your crush. It's not time to ask him out yet, so don't worry too much about whether things are going to lead anywhere. One conversation won't make or break whether or not you'll date, so try not to stress.
Don't worry about what your friends, or your crush's friends, think of you. Chances are slim that you'll end up alone with him in a room where you can talk privately, so you're going to have to talk to him in front of others. After all, does it really matter if someone eavesdrops on your conversation? If they do, then they obviously care too much about your life.
It doesn't matter if your crush is best friends with the hottest girl in town. Walk up to him and have a conversation anyway. Even though you constantly compare yourself to her, he's not going to compare the two of you.
The thought of approaching your crush is terrifying, but he's just a normal person like everyone else you know. What's the last thing you've spoken to your crush about?