When ever he/she talks to you, make sure you act bored and uninterested. Try looking at your nails, pretending to read something, writing something or just dont look at him/her.
Step2
When he/she tries to get your attention pretend not to notice them. Just walk on by or just continue doing what your doing. And if they dont stop say something sarcastic, or rude.
Step3
If they ever drop something just walk on by. Pretend not to notice him at all. AND DONT LOOK BACK! Because odds are they will be looking at you, and you'll probably be tempted to help them.
Step4
If you ever are tempted to be nice again, try acting as if you dont remember ever being mean to them.
Tips & Warnings
If your just trying to be mysterious this might not work that well because it might make he/she hate you.
Try not to over do it that much because then that person might tell others and you might lose friends and etc.
If you are just going through an I HATE YOU phase this might be taking it to the next level, so if that is the case then try not to over do it. Just act icy.
WARNING: After doing all these things the person might not try to talk to you or anything. So dont use it to attract attention from someone they might think your a bad person.
If its a love/hate relationship dont use this article steps because after your dont you might not have a boyfriend/girlfriend left.
Only use these if you actually hate someone and its not just you trying to cover up you other feelings.
Novice 
