Want to go camping (tent) at Khao Yai National Park anything I need to do in advance (such as reserving a camping spot)?

If possible try not to go over the weekend as it gets extremely crowded in both camping areas. I'm not sure if you can reserve a camping space or not, but if you must go over the weekend it would be a good idea to do so. We camp there several times a year and November thru Feb are the best months although some times in the evenings it can get pretty cold. Actually we are off to Khao Yai on Monday for a few days.

tip - if you go walkabout on trails during the day.. empty your tent & leave the 'doors' open. If you don't, chances are extremely high it will be torn open, its contents ransacked & strewn around outside by the resident troops of highly inquisitive pig-tailed macaques..

(some have even learnt not to rip their way into a tent, but actually unzip them. its funny to see, until its yours..)

tip - if you go walkabout on trails during the day.. empty your tent & leave the 'doors' open. If you don't, chances are extremely high it will be torn open, its contents ransacked & strewn around outside by the resident troops of highly inquisitive pig-tailed macaques..

(some have even learnt not to rip their way into a tent, but actually unzip them. its funny to see, until its yours..)

Very true. This is exactly what happened to us last month at Khao Yai. We should have known better as we have been camping there since 1995. The past several years the macaques have gotten very aggressive. When we left the camp site for a few hours we took our food with us but closed up the tent. The macaques, thinking their might be food in the tent, managed to get in and went through everything, leaving quite a mess.

anything I need to do in advance (such as reserving a camping spot)?

you can reserve, but only if you are booking & renting one the Park HQ's own camo tents.. the camp grounds are quite large though, so simply turning up with you own gear at any time (including weekends) you will find a spot to pitch..

..these are the 'cheeky monkeys' i mentioned earlier - a vid i shot a few years ago, Mrs G and myself are in the cheap orange & blue Tesco Lotus tent.. In my experience, expensive camping gear & hungry macaques (at least, the ones here) don't mix.

It was 11 degrees last night in Khao Yai! I had to have a big nip to get to sleep!

Hmmm, my "little nip was OK that day but it now seems its an illegal activity punishable with a prison sentence.

Its an affront to my Scottishness!! I am going to have som tam outlawed back home.