In the fall of 2010 we did our first trip around Southeast Asia. After spending couple of weeks in Thailand our next stop was Cambodia. As probably everyone else our main reason to visit was the world famous temples of Angkor Wat in Siem Reap.
Quick tip: If Angkor Wat is on your bucket list, make it a priority and go as soon as you can. Every year the million numbers of visitors increase drastically and soon will be impossible to even take a photo without anyone in it. We were lucky to have been there over six years ago and there were hardly any tourists around. Looking at some recent photos now there's people everywhere.
There are 3 ways to get to Siem Reap from Bangkok. The first is the easiest and fastest way of all but the most expensive way - flying. If you are on a budget though like we were you should choose between taking a bus or a train. Since we all have heard plenty of horror stories with scam busses, visa-rip-offs etc, we recommend going by train, which takes about 6 hours to the border town Aranyaprathet. As long as you do your research in advance and know what are you doing, the trip is very easy. We both love adventures and we used to would choose the cheapest way of travel, so we took the train.
Train from Bangkok to Aranyaprathet
There are two trains departing daily from Bangkok to Aranyaprathet, close to the Thai/Cambodia border. The first is at 5:55am, arrives at 11:35am, the second at 1:05pm, arrives at 5:35pm. We recommend taking the earlier one to avoid getting at the border by dark and getting stuck there. The train ride itself is nice and scenic and nothing to worry about.
Once you get off at Aranyaprathet you will see many tuk-tuks that you can get for a short 10 min ride to the border. Do not trust the driver if he promises you to take care of your visa or don't let any tout coming with you to assist you. Be prepared there will be plenty of them trying to scam you, just ignore them.
Don't buy your visa anywhere but once you get to the Cambodian visa office ( located after the Thai border exit ) and make sure your tuk-tuk driver drops you off at the actual border by the Rongklua market. There an official will stamp your passport upon exiting the country where you will be "in between zone". Walk across the border under the 'Welcome to Cambodia' sign and the immigration office will be on your right after a short walk.
The standard 30-day tourist visa used to cost US $20 at the border ( it might be $30 now ), and you'll need one passport photo. So make sure you prepare that in advance. At the visa office they will try to scam you again and ask for extra money, know that all you have to pay is your visa fee. That's it, you are in Poipet, Cambodia now but not so quite to Siem Reap.