one Learn how to be real with yourself and don't over-commit. You are never going to be able to make all the people happy all of the time and the more you try, the more jacked up your life will become. It's not easy to prioritize, but it's absolutely necessary. When you learn how to identify what is really (seriously) important and what is not, you will probably find that everything works out much smoother and you'll like yourself better.
two Have limitations to what you'll do for others. The more you give of yourself, the more people will come to expect. And then, when the day comes that you don't even have enough of yourself left for you - everyone who has come to rely on your diligence and attention will be all the way angry and disappointed in you because you let them down by not meeting their unspoken expectations. Learn how to draw lines in the sand and stop yourself from wanting approval so badly that you'll do dang near anything for somebody else.
three When you get on a commercial airplane they always do this spiel about how if the plane's going down and you have a shorty with you, you should always put the oxygen mask on your face first. I think the logic here is that you'll be of no use to anybody if you die while trying to make sure they live. Make sure you take care of you first and everybody else right after that.
BONUS FOURTH THING If you think you need to climb up that tree, you'd best have a solid plan to get yourself back down. Don't be getting all skidgy and whiny once you get up there as high as you can go and be expecting somebody to help you get down. If you were able to get all the way up that tree, you can bet your bottom dollar that you'll get your own bad self back down. (This can be metaphorical and applied to any number of different things for the rest of your life.)