Have fun and enjoy the experience.
I have a tonarment in 2 days

Is it a tournament on chess.com or in person? If it's in person be careful about touch move and touch capture those are my tips for you
I don't have many experiences of otb chess, but my experience was that the clock seemed to run out faster than usual, and the board vision was not as clear as when I'm playing online. My tips are to keep calm and prepare your vision to be used to a real chess board. Good luck.

Avoid taking free pawns in the opening to not get into some cheeky gambit
Use your time wisely
Prepare a solid opening

Take your time, you will feel nervous and want to move fast, whatever you do, do not do this, that is how I blundered checkmate to a 100 up 12 points in materail.
Any tips for otb tonarment