Tell them you love them often. Even when they've been little buggers, explain that it's their behaviour you don't like but you still love them.
Never go to bed on an argument. Always make up before saying good night.
Never let them walk out of the door on an argument, always let the last words they hear from you is I love you.
Remember things have changed from when we were young.
Appreciate the challenges social media brings.
Pick your battles.
Try and understand things from their perspective.
Remember that even though what they are worrying about may seem trivial to us, it can be huge for them.
Don't assume the teen years are going to be challenging- I loved them at this age. I had no issues either either of mine, after all the warnings I had of how difficult they would be, it was a pleasant surprise.