1)Use your high expectations as a method of motivation.

Instead of "I expect this", try "I know you can do this".

The expectations are the same, but it comes accross two entirely different ways: The former is demanding, the latter is acknowledging someone's skill.

2)Let the ball drop occasionally.

Believe me, a person learns far more from a good screwup than from someone rushing in to save the day. Don't insert yourself into things, but ask your coworkers if they need help.

3)When you must correct people, do it indirectly and put the onus on yourself. "Hi Joe, listen, I was just looking at this and I am getting different numbers. Could you run over this with me?"

Joe will likely then see his mistake, but you've let him save face.

4)Follow the 24 hour rule:

If something makes you angry, wait 24 hours before sending an email or talking to someone about it. This is CRUCIAL if you have a short fuse as you are likely to say things you don't mean or will regret.

5)Practice with a tape recorder.

If you are sounding sarcastic and don't mean to be, record your voice and listen to how you sound to others. You may be suprised. You may also wish to practice facial expressions in a mirror.