Get the paperwork sorted early
You'll need a FIDE ID before your results can be rated. If you don't already have one, most organising clubs — including ours — can request one on your behalf when you register, but it's worth doing this well before the entry deadline rather than at check-in.
Train the way you'll play
Long time controls reward calculation stamina more than opening memorisation. In the weeks before a rated event, it's worth playing a handful of slow, fully-clocked practice games rather than only blitz — the two skills don't transfer as cleanly as players expect. Reviewing your own recent games for recurring mistakes is usually more valuable than studying a new opening line.
Plan your tournament week, not just your games
Multi-round events are as much about energy management as chess ability. Build in time to eat properly between rounds, and avoid deep post-mortems on a loss right before your next game — a short walk does more for your next result than an hour of regret.
On the day
Arrive early enough to find your board without rushing, bring a working chess clock only if the venue requests it, and read the tournament's specific regulations on electronic devices before round one — most FIDE-rated events now enforce a phone-free playing hall with immediate forfeiture for violations.