Coming from someone who has a bit of experience in this area I have a few pointers.
1. Before a relationship: Do not get attached too quickly as a previous poster stated. If things do not work out it will really help and reduce the amount of pain and increase recovery time greatly. When you get too attached too quickly and things do not work out, you will be left thinking about that person you are now attached to, and not be able to get them out of your mind no matter what you do and it will give you pain thinking about them all day long. So as a rule of thumb, do not get attached too quickly. I recently was getting interested in a girl and started to get a little attached and I was starting to not be able to do anything but think of her or wait for text messages or phone calls. I quickly snapped myself out of it and told myself we are just friends and did not let myself get attached. Right now she is my friend and I do not think about her all day long, which I cannot tell you how much it helps.
2.I would be very cautious about jumping right into relationships from the beginning also, unless you know for sure God is speaking strongly to you about it and not your lust. If you are interested in somebody, just be their friend and see if its somebody who you really like to be around and see if she has all the qualities you want in a woman, then, if its meant to be, it will lead into something more and if not then you just have a friend.
3. If you are in a relationship or just starting one, do not get too touchy and feely. Although its extremely difficult to resist, being physical can take your mind off the real qualities you desire in somebody and blind you with the "fuzzies" or "stars" or whatever you call them. I had to learn the hard way.
4. Dealing with a breakup: This is the hardest to usually deal with because you are now broken up with somebody who you probably shared secrets with, spent a lot of time with, gave your trust to, and so much more. It's basically like losing somebody very close to you, especially when you are on the receiving end of a breakup where you were the one who wanted to continue and the other did not. The first thing you really have to come to realizing is that "its over". I let my pain drag on forever because I couldnt get past this part. For months I was hoping we could still work things out or that she would call me even though we never talked once since. It took me a long time to get to the "its over" realization stage. Once you get to that stage, you can begin your recovery in which only time and prayer will heal. You can add things in like doing some recreational activities or being with your friends to take your mind off the person which will help. It will not help if you are still not past the "its over" stage though because you will always be thinking about them and hoping things will still work out and maybe they will call you or thinking about some new guy she may be with and the list is endless. So really the biggest thing you can do to help during a breakup is.. move on. Do not let your feelings drag on for her. Pray that God will heal your heart and recover. Get some friends or find some recreational activities to keep your mind off her the best you can.
Hope this helps a little.
John.