Well if you dont want to see the chick again but she seems to want to, this works best (note, you must be at your place for this one): In the morning if she starts getting all lovey dovey with you, roll over give her bus fair and tell her she knows where the door is.

If you are at her place and you just wanted the 1 night stand, wait till she falls asleep and get up and leave, dont leave a note, dont leave your number, dont leave anything, just leave.

These work great as I have used both a number of times, the chicks will NEVER attempt to make contact with you again and if you do happen to run into them again they will completly ignore you.