Here's just a few examples gathered from friends .... feel free to add your own as a reply comment.
1. Be impeccable with your words (speak with integrity, don't gossip or talk bad about others; it will come to haunt you).
2. Don't make any assumptions (ask questions and expres what you really want; communicate with others as clearly as you can to avoid misunderstandings).
3. Don't take anything personal (nothing others do is because of you; what others say or do is a projection of their own reality and issues).
4. Always do your best (your best is going to change from moment to moment; it will be different when you are healthy or sick. Simply do your best and you will avoid self-judgment and regret).
Always be on-time
Anticipate what can go wrong
Don't bad mouth colleagues
Find responsible people to whom you can delegate
Don't lose your temper (it's OK to swear in private)
Learn to take very deep breaths.
Don't stop working at a problem until it is solved.
The customer is your partner and treat each engagement with the customer as such - a win/win for all.
Focus on your strengths.
Acknowledge what you have accomplished rather then what haven't.
It is okay to question yourself but never doubt yourself.
Never underestimate yourself and others won't either.
Never, ever disappoint a customer.