I just took a look at the site of new Irish friend Justin MacCarthy, who recently traveled to Thailand and Cambodia and may be in New Zealand when we're there. I saw a couple of great posts about practical advice on Thailand and Cambodia.

 Hook up with a local to drink beer on the train...

I thought I’d buy a large bottle of Chang beer to share with my new friend. I called the carriage guy and asked him how much a bottle was. 170 Baht. Ok I knew it would be a little more but the usual price is more like 70 Baht. I was about to say what the hell and buy one, when I saw Tawat motioning not to buy it. No thanks I said.
When the carriage guy was gone I asked Tawat what was up? For you, he said, its 170 Baht, but for me its 100 Baht. He smiled. Yes we charge foreigners more!! So Tawat bought the beer from then on. And our carriage guy laughed it off. So if you want to buy beer on the trains, get to know a local!

And, a really interesting look at his first arrival in Cambodia. 

I knew arriving in Cambodia would be a shock. I had never been to S.E Asia. I had never traveled alone. I knew it would be a culture shock. It was, in spades. For first few hours I thought I’d made a mistake. 3 weeks later I’m fascinated by the country. Hopefully we'll see Justin on the trip soon...