unfortunately any definite rule i have made for myself I have broken, but I have also been very different people at different times of my life so I don't know that this is neccesarily a bad thing. Sometimes forcing yourself to follow a code that is disingenuous to what you want and or who you are is more detrimental than being honest and contradicting yourself.
That being said, we all unconsciously have boundaries that we do not cross or things we hold sacred. For me the things that I have done and respected consistantly I did because they are things that I believe and understand at my core and so flow from me naturally and genuinely, usually without me awknowleding them. This is not an argument for unconsciousness however, you can, and I HAVE hurt yourself and others when acting in blind fear. Generally the rules I have in my heart are this;
1. Value life. Do not assume my political opinions from this statement. Whether random or intentional, life is delicate, powerful, violent, beautiful, and miraculous. As anything else, we consume and destroy in order that we live, but it does not mean we do not recognize it's value, respect it's power and our dependence and entanglement with the rest of the world. Don't kill/consume uneccessarily and be grateful and not wasteful with the resources provided you.
2. Follows from one, respect people. As Scott says, "appropriately." You do not have to revere them or take abuse, but be careful when you start to play the "me vs. them" game. They are human, so are you, they are not all bad or all good, they have value, as do you.
3. Forgive. Funny enough, it's hardest for me to forgive myself, to not let one little mistake snowball into a crushing mountain of guilt and self-loathing. Thing is, when you believe you are a failure, ****** up, selfish, and stupid, you begin to make those things true. Call it a self-fulfilling prophecy, call it the Law of Attraction, but the energy you put out is returned to you. Forgive yourself because you know inside of you that you are a better person, give yourself the gift of awknowledging that better person. Buddhists call this "prajna," the potential to be better that you carry always inside you.
I haven't and probably won't have these in mind at all times, but I hope that I can be my best person at least some of the time.