I would offer the same advice for an OTB tournament.
Get plenty of rest.
Prepare by doing tactics. TAKE YOUR TIME. You want to warm up your brain just like yo would warm up before exercising.
Stay hydrated. Water is best. Stay away form sugary drinks, and energy drinks.
Eat a light meal.
A cup of coffee 30 minutes before the first round.
Use a real board and pieces. You want to simulate OTB conditions as much as possible.
TAKE YOUR TIME. There is absolutely no need to rush in a Daily chess tournament.
Write down your thoughts, ideas, plans, etc. Obviously his cannot be done in OTB play, but its a great learning tool for online.
Play the position on the board, not the rating.
Most Importantly. Have Fun!
Good Luck!
The lowest rated player I saw was a 1300 and the highest I’ve seen was a 1800 or so.
Also it is a daily tournament