I think I unederstand what Leonard is talking about.
When it comes to making new friends it depends on what you are looking for. I am assuming you are looking for the kind that are more socially active (such at partying etc.), it just takes confidence. Get to know people and put yourself out there. It may seem difficult especially for more reclusive people but it's simple. Confidence can work wonders - and if you are intimidated do not be. Everyone is self-concious and insecure, they feel the same fears you do. Just try to meet interesting people and have a good time. No one is going to make you have a good time in life. If you want to have fun, be productive, and live to the fullest then fucking do it. Teens these days run on popularity, unique-ness, and being outgoing. Everyone whines about how different they are and no one liking them, it's silly. In case you have yet to notice - every single teenager wants to be different and cool. It just depends on how you go about it. Obviously you will have to conform a little to make certain friends, but no one is forcing you. There are people who are true to themselves and have a great time with many friends.
My best advice is to think well of yourself and be courageous enough to get yourself out there.
Make an effort to be noticed. If you have issues - whatever they may be - with talking to unknown people or going outside of your comfort zone, simply fake it. I don't mean to lie about yourself, but hide your fear.
It isn't necessarily bad to be full of yourself a bit, no one is going to give you the recognition you deserve but yourself.
Try to make common ground via interests, points of view, or experiences.
It also doesn't hurt to take an analytical approach if you are unsure what to do. Those popular kings and queens are human beings just like you, blood courses through their veins just like yours. You can engage in conversation with anyone, social tiers are figurative.
It depends what you want in life, no one is forcing you to go out and party, and no one is forcing you to be by yourself. This goes to anyone reading this, and fuck this post is huge.