Lots of good (and bad) advice here already, but here are my 5 cents:
Being more outgoing. There are two steps here that need to work for that to happen: you need to like the person you are in social situations, and you can't care about what people think of you.
To elaborate on the first point, you need to enjoy social situations. Don't go into social situations to "meet friends" or get "rid of you social anxiety" - go into them to have fun (here the second step needs to be in order, but more about that later). If you have fun, you'll meet people who you think are fun to be around with - and there's a good chance they think the same of you at that point. Also, liking the person you are usually includes things like not being arrogant etc (for most people anyway).
The second point: don't care about what people think of you. This doesn't mean you shouldn't care about what people think - they can have interesting, magnificent, cool ideas, but it's just their opinion of you that shouldn't matter. As long as you like the person you are (see point above), no one else's opinion should matter. I have maybe 5 people in my life whom I'd listen to if they said seriously commented on something about me. It's very hard to express yourself openly and have fun if there's something in the back of your mind telling you how you should care about what all the people present think of you.
In my experience, you can't have one without the other. Both of those need to be in order to actually enjoy being around people.
Then, your study habits (remembering crap when trying to study). I had (well, have to some degree) the exact same problem as you. I can't say I've found the magic bullet, but I think I've got the basic psychology down. Think about what you do when that train of thought starts to appear? I'd bet good money you hold out for a while, but eventually give in and watch a movie/new episode of House/play WoW/etc. That's a pattern your mind has learned over the time: if you start thinking about crap you'll eventually get rewarded with the latest antics of that funny doctor. Breaking that pattern is hard, but if you have got the socialization part down, it becomes easier, as you have much less embarrasing things to care about. As soon as you start thinking those thoughts, you need to redirect them to the task at hand. And again. And again.
Throughout all of this, one important skill is redirecting your thoughts. Find yourself at a party, thinking if the thing you just said was maybe a bit awkward? You need to redirect your thoughts to the task at hand, having fun. Talking to a new friend, thinking how you should respond so he'd think good of you? See previous action. Thinking about crap while studying? Redirect your thoughts to that funny thing that happened last week or the task at hand.
Obviously it'll take a long time before you change your thought patterns permanently, but don't despair, you're only 21.
Being more outgoing. There are two steps here that need to work for that to happen: you need to like the person you are in social situations, and you can't care about what people think of you.
To elaborate on the first point, you need to enjoy social situations. Don't go into social situations to "meet friends" or get "rid of you social anxiety" - go into them to have fun (here the second step needs to be in order, but more about that later). If you have fun, you'll meet people who you think are fun to be around with - and there's a good chance they think the same of you at that point. Also, liking the person you are usually includes things like not being arrogant etc (for most people anyway).
The second point: don't care about what people think of you. This doesn't mean you shouldn't care about what people think - they can have interesting, magnificent, cool ideas, but it's just their opinion of you that shouldn't matter. As long as you like the person you are (see point above), no one else's opinion should matter. I have maybe 5 people in my life whom I'd listen to if they said seriously commented on something about me. It's very hard to express yourself openly and have fun if there's something in the back of your mind telling you how you should care about what all the people present think of you.
In my experience, you can't have one without the other. Both of those need to be in order to actually enjoy being around people.
Then, your study habits (remembering crap when trying to study). I had (well, have to some degree) the exact same problem as you. I can't say I've found the magic bullet, but I think I've got the basic psychology down. Think about what you do when that train of thought starts to appear? I'd bet good money you hold out for a while, but eventually give in and watch a movie/new episode of House/play WoW/etc. That's a pattern your mind has learned over the time: if you start thinking about crap you'll eventually get rewarded with the latest antics of that funny doctor. Breaking that pattern is hard, but if you have got the socialization part down, it becomes easier, as you have much less embarrasing things to care about. As soon as you start thinking those thoughts, you need to redirect them to the task at hand. And again. And again.
Throughout all of this, one important skill is redirecting your thoughts. Find yourself at a party, thinking if the thing you just said was maybe a bit awkward? You need to redirect your thoughts to the task at hand, having fun. Talking to a new friend, thinking how you should respond so he'd think good of you? See previous action. Thinking about crap while studying? Redirect your thoughts to that funny thing that happened last week or the task at hand.
Obviously it'll take a long time before you change your thought patterns permanently, but don't despair, you're only 21.