I've discovered that since I've began taking detailed notes, I rarely tilt.  The notes help me focus on the decisions I made throughout a particular hand, and forget about the result.  It's always important to remember, especially if you're a beginning player, that the results of an individual hand are not as important as the decisions you make in the hand.  You have no control over the cards that are dealt, so you need to make sure your decisions are correct.  After thousands upon thousands of hands, you will see that the results will work out in your favor.  If you stay narrowly focused on one hand, you will never improve your game.

One important thing about taking notes is to make them as detailed as possible.  Simply labeling someone as a "donk" or a "fish" won't help  you down the road, and it will more than likely just make you tilt worse.  The idea behind taking notes is to pick up on players tendencies, and try to figure out what range of hands they're calling/betting/raising with.   What position were they in?  What were they blinds?  What was their stack size?  What cards were on the flop, turn, and river?  All of these are things you should ask yourself as you take notes on a player.  These details are important when you're trying to figure out why a player made the play he did, and can help you in the future when you run into the player again.

What I usually do when I'm taking notes is open up a replay of the hand I want to take notes on.  This way I can still focus on the current hand (and any other tables I am playing), but still have all the information I need for my notes.

One final word on notes:  Just because you have notes on a person being a maniac or a fish, never discount the fact that he just may have a hand.  Know when you're beat, and don't shove or call just because you're up against a donk.  Your stack will thank you.