Never become the cause of anyone's resentment.
Life's too short, always have desserts first.
Let people learn their own lessons. There's a difference between interference and intervention.
A person's true character is shown not when you're friends or lovers, rather after that. There's a reason why there both kind of people in the world - the ones that stay in touch with their ex, and the ones that don't.
Don't take karma in your own hands. The Universe always has your back, trust its justice to be much higher and more creative than yours.
Never force someone to do something. Respect people's wishes and space - if they're genuinely interested, they'll agree without your pushing.
Don't ridicule someone. Theres always something to learn from anyone that crosses your path.
No work is too pety, as long as you do it with dignity. Not even cleaning the bathroom.
Your dating life can wait. SERIOUSLY. Become emotionally, mentally, physically and financially stronger, otherwise you'll get yourself into a downward spiral that takes you years to recover from (and sometimes, never). We don't need more bitter, given-up-on-love people anymore, thank you!
Don't repeat yourself. If someone hurts you the second time, or they don't get the message the first time, move on. You're wasting time after the first attempt.