1) Say No.
(No thank you. No, I dont want to.) There is no substitute for saying No!
2) Repeat No as often as is necessary.
3) Use Body Language that says No.
a) Serious facial expression that shows you mean No
b) Hands up, hands out gesture that says Stop.
c) If everything else fails, use your strength to push away and say Stop.
4) Suggest alternatives that can build the relationship.
(Lets go to a movie, Lets go for a walk, Lets make dinner together.)