Probably my best and shortest advice as someone who has been in a marriage where I had to be both mom and dad, as a single parent, as a stay at home parent, as a stepparent, as a co-parent in a terrific marriage, and finally as a parent who is learning how to step out of being a parent since my kids are 23, 25 and 26. Whoa...that was long winded, but I guess my point is that I understand the dynamics of being a parent and I have nothing but compassion for those of us still struggling to be good parents.
* Love your kids with all your heart
* Give them as much affection and time as you can
* Provide strict structure and discipline (I use the word strict because by today's standards strict has de-evolved into reasonable rather than the excessive permissiveness that permeates our society.)
One of the things that used to drive me nuts was getting the kids on time to the dinner table. I would get very upset about this because I would spend time and energy preparing a nice home cooked meal and repeated shouts for the kids to come down from their rooms would be in vain. Meanwhile the food would be getting cold and I would be getting hot!
With teenagers it is useful to ask yourself this question: Whose problem is this? Eating cold food was not my problem and the great thing about natural consequences is that they teach a direct lesson much more effectively than a parental lecture. If I forget to pay a bill on time there is a late fee. If losing the money is important to me than I will make darn sure that I pay my bills on time.