One thing to be aware of during major Thai festivals is over crowding.
It is not uncommon to have over 30,000+ people at some festivals.
With that many people comes many, many problems.
Traffic is a huge problem and finding a place to park is impossible.
Not only getting to the festival, leaving as well.
Avoid people who have had too much to drink.
Large crowds draw all the professional pick-pockets so guard your stuff carefully.
Do not carry anything in your back pockets.
People can be crammed together whether sitting or standing, with no space to move.
Thai’s like to eat at outdoor festivals and leave their trash all over the place.
The crowd noise can be extremely loud as well.
If you understand all these things, you can prepare yourself.