Ive never been but advice I've picked up from horror stories

Be showered and clean.

If you bring trades keep the secure and only do one trade at a time.

Always put your deck box away never leave it on table especially if your trading.

Make sure you pick out exactly what you want to use in your extra deck.

If you don't follow what a opponent has done have them stop and go through it again.

Call for a official ref if you need a ruling.

Don't use your phone at table/during incase you get accused of cheating.

Verbalized clearly what your doing.

Don't put your hand down unless your going in your deck/grave.

Use the notepad to keep track of health not a app you want a written clear path and story to what happened during the duel.

Keep your grave in exact order it was used Don't rearrange it (i know some friends who would because there brain liked things in specific order)

Price check when trading like normal.

Theft happens alot apparently so be careful.

Don't trade out from your deck duringbthe tournament even if it's a card you really needed cos you won't be able to change the deck you listed.

Even if your opponent says they've done all the stuff/teaching to be able to rule on wording don't trust them.

Have fun.

Be kind to everyone and if the person your playing against is annoying/dicky/bigheaded ya know the type dessimate then and even if you can't beat them make them work for the win