This may sound crazy - but I find that telling my kids about some of the stupid stuff I did as a teen makes me more accessible to them.
It's one thing to say to them "I've been there" but when you tell them an actual time when you made a big mistake, and got through it - then it makes you seem more human, instead of like yiu ae always trying to be the perfect example.
Also, whenever I make mistakes with them today (yelling at them, accusing one of something the other one did, etc.) I apologize.
I think too many parents think they have to keep up this "I'm the parent so I'm always right" front. They think that is the only way to be in control of their kids. But teens know that parents make mistakes, and it is more important for them to see that we care more about their feelings than us always being right.