Hi Indigo
I think becoming more extroverted takes practice. My first year of college I was so shy I think I completely forgot how to even say 'hello' to someone. It takes time. It's hard to describe.
I think you have to focus on getting out of your introvert zone and even say 'hello'. I'm still not good at small talk, but I'm great with a smile and hello. Plus when you're in school and in a class you do have one thing in common - the class you're taking. I also use humour as well. I'm not a really funny person but I'm goofy which I think is really non-threatening to people. Make sense? In some ways I'm the opposite of 'cool' but then most people are. They may look like they have it all together but kept in mind nobody does - ever. They feel just as awkward and insecure as you do - some more then others, but no one is perfect.
Anyone else have some suggestions????
Hope that helps. I have to think about it some more. It took me a long time to work on this.