Managing expectations really seems to help me. Over the years, I've come to the realization that my expectations of others, and myself, were unrealistic.
Recent experience really brought the 'managing expectations' point home - in dealing with a few people whose standards were too high (and in one case, even worse, they were not only unrealistic standards, but also, ever shifting O_O). This sort of thing left them frustrated a great deal of the time. They had/have a lot of things about them that can benefit others, but the negativity is something that others pick up on - which doesn't help.
One other thing that helps with managing anger is just being an observer of things. Keeping a cool spirit. Realizing that anger can be a trap and a snare. When we see this happening to others, we know we don't want to go there!