you must have some people you can go mingle with, go do that for a few lunchtimes, see who tlks to you, build up your extended friends network, see who likes you best out of the first group, go witht hem to the 2nd group voilaa, lots of friens, also just (and i kno its bad) (assumin u have msn or simular) just ask someone on ther who u knwo is poop ular for X,Y+Z's email adresses get tlkin to them and build from tht!!!
hope it helps, its not impossible, another sure fire way, just sa one lunch whos comin to the pub.. you wil be a god!!!