for the college people: getting into groups/clubs at school helps to make friends... there's usually a campus crusade group available or just join a group that you have no experience in or something that just sounds like fun (a martial arts group, a fencing club... i know nothing about it and i stunk at it but it was good for laughs, etc.) there are TONS of groups available... just ask for a list of them from the student center in your school.
working people: church is an awesome place to get to know people, if you really like you 'home' church then stick with it... but if there's another church that has bible study groups that are related to your age then get involved... there's no rule that says you have to stick with everything at one church.
mission trips/ conferences... obviously you don't go on those trips to meet the future mr/mrs right, but, hey, maybe God is showing you someone that you can respect and look up to as a Godly man or woman
joining a gym (again... there are tons of classes to choose from... you never know what you'll find!),
*these can apply to college people too*
I had an awesome mentor tell me... just keep running the race with God. you can do so many things that married people can only dream of doing. you aren't tied down to anyone or anything (not that that's a bad thing). you have the ability to just pack up and go wherever God leads. Enjoy every moment of the race... just you and Dad (God). Then, one day, He'll let someone join you two in that race... and as you're on fire for God, that special someone will see that fire. and if they are running that same race with God... on fire for Him... the day that God joins you two... that fire will burn like no one has ever seen.
I dont know if that last part helped or made sense... but there's a little more input... enjoy!