If you've recently had a breakup...

I know it's hard, but especially right after a breakup, the best thing you can do is to give your ex some space. You may want to get her back desperately, but you have to remember that there was a reason for the breakup. However much you disagree with that reason, you need to respect it by giving the relationship some time apart. It's possible that healing was needed between you two, and that after some time has gone by you are able to get things back together.

After a break... you've had some time to level out from the relationship.

It's important in your time apart that you do your best to let your emotions heal. If you were hurt, forgive. Even if it wasn't your fault, forget about it. If you're going to try to get this relationship back together, you are going to have be humble and also patient. Remember, it may take more time than you were expecting or than you thought you were willing to give.

You're ready to try to get things going again!

After you both have had some space... you should try contacting your ex. Maybe ask to meet for coffee sometime soon. This is a casual get-together. Talk about fun times. Remember though, this is not a time where you beg to get things back together. Just try to have fun and try to detect if there are still any old sparks that remain. If this coffee time works, maybe try to do it again in a week or so. You want to take it slow.