#1 - DOTE ON THEMthe more you can give someone, the more they will like you. bend over backwards if necessary. (pay no attention if they take advantage of your kindness, it will pay off)
#2 - DIVULGEtell them secrets. tell them secrets about other people, break confidentiality, put yourself at risk. you definitely want the kind of friends who are nicer to you when they know they can gain valuable information from you.
#3 - DON'T GIVE UPif at first they seem to stay a little distant, persist, persist, persist. eventually you will break down their defenses. see #1 and #2 for a surefire way to achieve that goal.
#4 - DISHshare gossip with them. take their side against every person they despise and help them trash talk those people at every available opportunity. bonus points if you can make #2 apply here.