2) Recognize that it is over - and actively decide to leave the past behind and move on with your life.
3) Don't contact them at all. It is hard to move on, and to start again, if you keep them in your life.
4) Avoid the places you know they tend to be; only see mutual friends when they are not around.
5) Go out with your friends, don't stay at home on your own. If you're out having fun, you will think of them less often.
6) Realize; realize that you deserve better. And realize that if they were the one, they would still be in your life. But since that is not the case, you will find the right one.