So, to summarize...
Never post your email or contact information publicly.
Only communicate with the seller via Direct Message. You will share your information and they will share theirs, via the DM...only.
Once the deal is consummated and all is well, you can leave feedback for the other party, as they can for you.
If anything goes sideways, try to work it out with the seller first...and if no joy, then make a report to staff...and we will look into it. But we are limited in what we can do.
You can also post in "Feedback" if need be...to alert the community and get their perspective if things go awry.
Welcome to BF...hopefully you will enjoy your time with us.