It's worth remembering that the pond is very small pool at secondary school and gradually it gets a little bigger at college. More like a full blown lake at Uni. The reason being is purely of the numbers and the backgrounds of all the people attending.
Be patient, and be relaxed, open minded and kind. The majority of people love to talk about themselves. So if you listen carefully you will be a winner without even saying very much. Use any time you have to explore every experience you can find to try or have a go at. Pick up on subtle invitations to join in (anything) and don't end up shying away from group meets. It can be very hard forming bonds with other people but don't give up. Try and be friendly and happy and people will naturally gravitate toward you. Share activities - try everyone out from A to Z and find your own passions, or sport, or drama, or music. Be brave and be patient. Growing friends is like growing crystals. Eventually you will share and find good people to spend time with.
You need to know more about yourself as you get older just to find all the cr*p you have had indoctrinated into you from your parents, relatives and at school was a complete waste of time and nothing like the truth. Then you can talk about it. Learn to trust your own experiences and own mind. Most good friendships develop when someone else shares your general outlook, sense of humour and life values or you have a vested interest in helping each other in some crazy kind of symbiotic relationship.