I went to SR last dec as part of a community service program. My pointers to new visitors is as follows:
1) Cambodia is using USD hence some of the stuffs there they markup by alot (close to 300%).
2) Some attractions tourists got to pay triple the price.
3) AngKor wat is a nice place but u will get bored soon once inside there cos all u see is ruins, ruins and more ruins

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4) Ard ang kor is all the other kinda ruins like Ta Prohm, Ang Kor thom.. quite interesting. However, the ancient staircase are a real challenge - easy to climb the staircase, but difficult to come down esp if u got fear of heights...
5) The most popular markets in SR are old market and night market. Most of the shops there all sell similar items... u will get sian going up and down. Always be on guard to bargain the best price..
6) See if u can get used to cambodian food - chances are most singaporeans wont! cos cambodians use some special kind of garnishes - u juz feel like puking out... if there is one thing i enjoyed in the cambodian food, that wud be Amok Fish in Coconut milk.. the rest i wont recommend, u rather opt for western food.
7) The restaurants u gotta wait very long for ya food.. most of it la..
Thats my 2cents worth

Enjoy ya trip!