This has been my MO for making friends since I was in school. It doesn’t guarantee the coolest friends or the greatest cliques but it will build up your social circle solidly.
(1) Find people who are alone (their friends are in class or they’re new too or they went to a bar alone or they have brand new friendster accounts, whatever)
(2) Befriend individually
(3) When opportunity arises, introduce each new acquaintance you make to the other.
(3a) Opportunity can be something as simple as setting them up on a date or being in the same class or one needs help fixing their computer and another one knows how to fix computers
(4) In short, be the guy who builds social connections between strangers and your social circle will grow
Simple, common-sense and universally workable.