So it would appear you're at least somewhat aware of the fact that you're scared to make friends. But not really ready to try and get over it. You need some tips on how to better hide inside your insecurity and shut all new people out. Well go no further because here is your one stop shop on how to self sabotage.
Nail your resting face
Practice in the mirror, push and pull until it's in your muscle memory. Make sure that your resting face is unapproachable so anyone who may attempt to meet you will be deterred by something you aren't even thinking about. Be sure to find the right balance between angry, sad, and a little bit evil.
Find alternate routes
Back roads are going to save your life! Figure out where the alternate path is in order to avoid people who may want to join you on your journey. At any given moment you should be able to make a turn in order to avoid people. Hone your friendly person radar and slip away unnoticed.
Find where to sit
Now obviously this article can help anyone. But since I'm in school it's something on my mind so here's a school specific tip. IT'S NOT ENOUGH TO SIT AT AN EMPTY TABLE! Always scan the room and find the table that goes unnoticed. Because for whatever reason sitting by yourself is societies biggest social tragedy. When in reality half the population really don't mind it or even prefer it. In order to avoid people inviting you to move to their table you have to never give them the opportunity.
Wear armor clothing
Take unapproachable to the next level! Make it almost impossible for people to approach you by wearing clothing that doubles as armor. Obviously people will be turned off by this in the first place and probably won't approach you at all. On the off chance that they still REALLY WANT TO KNOW YOU. You can move on the the next option.
If you've read any of my articles, you know that this is always a valid option. Just get the heck out of there. It really is a big statement when you'd rather put physical strain on your muscles than deal with small talk and telling people what your schedule looks like. If you choose to use this option often you;ll start to see physical benefits as well so there's that.
Become a Shepard
Change your career and become a shepard. Make sure that whatever you talk about is shepard related. No matter how many times the subject is changed in a conversation just bring it back to how much you love being a shepard. Talk about your sheep, how the person you're talking to reminds you of your sheep, your shepard stick thing, and how much you prefer sheep over people. Word will spread that you suck at holding a conversation but rule at sheepherding. The conversations will stop and the job offers will roll in.
Hopefully you feel fully equipped to make no more friends. You don't need any more friends. Go hide in a hole.