How do you treat children with respect?

Teenage is when they grow up from little child that needs total care to older child that wants to do things alone. Give them some freedom, the older they get the more, but of course put sensible limits to their freedom and remind them those limits are still there.

Give them privacy. If they don't want to talk to you about something then don't make them, unless it is something that you are required to know, for example grades and school in general, and there are some rare cases where it's just better for them to talk about it, even if they're initially unwilling. You will just need a certain parental sense to find out when it's time for that.

Make sure they know about the dangers of drugs, drinking and sex and so on in time. Usually school should teach them early enough, but it shouldn't hurt to ask a quick "are you aware of that?".

And finally, show/tell them you still love and support them and are there for them, though of course not excessively with permanent cuddling and such if they don't want.