Forgiveness and letting go are key.  Here is a great technique:

Visualize the light of God shining down on you, breathe in, think of the person you need to forgive or let go of.  Saying the person’s name, or just remembering their face. And then breathe out, sending a sense of and love to them. People, you know well breathe in and out three times and more distant acquaintances only breathe one breath. 

As well as individuals, one can send love and forgiveness to groups of people, especially if you have ever been antagonistic towards them.  You visualize the group of people may be a workgroup or any group that you have had angry thoughts about, maybe the entire government! Send love to them. If you have any hatreds or antagonisms for groups of people you can breathe them in and out en masse. It can be a whole race of people, a country, a football team, a town or whatever.

Doing this act of forgiveness and love acts as cleaning for your mind, body, and soul.  It cleans up your energy field too!