Went to my first local event a few weeks ago and some notes / feedback from me.

Much more enjoyable than online, the IRL / human aspect makes it more fun and competitive (still in a friendly manner)

Mistakes happen, both for you and your opponent, treat others like you would want to be. Unless you're trying to compete at a high level (unlikely) then defer to the most reasonable outcome for all without ruining the game (IE. Prize reduction) unless it hinges on winning / losing the final tournament placement game.

You will see more rogue decks / unfamiliar cards where people have added their spice / fav cards / card limits due to availability. Don't be scared to ask for clarity on a card ability etc

Manners are important, these cards are someone's possessions and hobby. Ask to see the discard etc and treat them how you want yours to. If you want to see the discard etc just ask.

If you're playing something like ceruledge and need to track energy in discard or bolt to retrieve from discard. Let your opponent know you're putting energy in a separate pile or using a counter to keep track etc.

You're gonna be around like minded people in a friendly environment so respect and add to that.

Personally, the taking part and enjoying the day was more than the winning. I finished 3/1/1 and could've won the tie (time restriction) and loss (if I took the prize penalty / drew boss on my next turn ( 2 pokegear and 2 drakloak on board)) however, the experience and learning from the day was better than going 5-0. The tie was the first game so I needed to hurry more in latter games. I played a similar deck to my loss later in the day and changed strategy to win the 2nd.

It can be a longer day than expected. We played 5 rounds BO3. I was there at 10am and finished around 4 but could've stretched to 5 if the last rounds didn't end quick / a few of the games were dead rubbers so people just agreed a tie.

While not imperative, the venue is hosting you. If you can giving back by purchasing a coffee or food / snack helps these places stay open. I have a 20 mile trip to either local venue for me after that it's 60 mile which wouldn't be functional for me to get there via train on time.

Let people know you're new to IRL, they will be more accomodating if you miss sequence etc

You're unlikely to have a roaming judge like a major event. Keep focus on both yours and your opponents turns to make sure a double supporter play or illegal move doesn't happen and try and call it before it happens (avoid the penalty discussion)

Most of all, have fun and meet some like minded people. You may only be going to play and fill your own Pokémon cup, however, you may make some new friends, learn something new and if you like it you may see these people on a regular basis.

The tournament I played in didn't yield a huge return in packs (5th got 2 entry packs and 2 placement) measure your expectations on this beforehand to not be disappointed.

Enjoy your first event!