This will most likely be decided by your budget.
Overall, share-taxi transport is the quickest and most comfortable way to get from A to B. The share-taxis are nearly all Toyota Camrys. Try to get a left-hand drive one if possible, though most seem to be right-hand, suggesting they have been smuggled in from Thailand. Share-taxis run on a per seat basis -- you buy one seat in the car. Note that in a share-taxi, the front passenger seat is actually considered two seats, so the best option is to buy two seats and have the whole front seat to yourself, although then they often seem to sell a second seat next to the driver, which will invariably end up being half yours. Share-taxis leave when full, meaning at least five to six passengers, though once you leave the driver may pick up more people. We have ridden in one Camry with 12 people from Battambang to Pailin.
Bus travel in Cambodia is good, cheap, not too slow and reasonably comfortable. The main disadvantage is that not many buses leave in the afternoon. If you're planning on travelling by bus, figure an early morning departure as being probable. Buses run all the major trunk routes, such as Phnom Penh to Battambang, Siem Reap and Sihanoukville. You are not expected to share your seat on a bus, but be sure to get on early to make sure you actually get one.
To be honest, we're yet to try the trains (except the bamboo one in Battambang). All reports say they are very slow and very cheap, but for budget travellers who have the time to spend on them, the reports are positive. Trains tend to leave on time.
A number of trips can be done by boat, with Phnom Penh to Siem Reap being the most popular. Others include Phnom Penh to Kratie, Sihanoukville to Ko Kong and Siem Reap to Battambang. Overloading of boats often takes places. If you feel the boat is so overloaded to be unsafe, get off. They'll be another boat the next day. When the Tonle Sap is low, boat travel between Siem Reap and Battambang is not a good idea. Although comfortable and scenic to sit on the roof, be sure to bring sunscreen as you'll otherwise get burnt to a crisp.
Please find below some of the more frequently asked questions (FAQ) people have about travelling to Cambodia. We've tried to answer all the most frequently asked questions, but if you have another query about Cambodia, please try our Travelfish messageboard.
Is a fan room okay, or should I budget for air-con?
Is it possible to rent rooms or dormitories for longer periods of time while travelling in Cambodia?
Should I take my own padlock for the door of my room while travelling in Cambodia?
What should I do if a bag is stolen from my room or dormitory while travelling in Cambodia?
What standard of accommodation can I expect for US$5 in Cambodia?
Why are there so few dormitories in Cambodia?
Why are there so few hostels in Cambodia?
Can I drink the tap water in Cambodia?
How can I avoid MSG in Cambodia?
How do I avoid peanuts in Cambodia?
I have a food allergy -- what should I do when travelling in Cambodia?
Is there good vegetarian food in Cambodia?
Is western food available in Cambodia?
Are the ferries in Cambodia safe?
Are the trains in Cambodia safe?
Do the trains run on time?
Is it easy to hitch-hike in Cambodia?
Is it easy to rent a car or motorcycle in Cambodia?
Should I get a tourist minibus in Cambodia?
What is the best way to get around Phnom Penh?
Are credit cards accepted in Cambodia?
Are there ATMs in Cambodia?
How can I have money sent to me in Cambodia?
How can I send money out of Cambodia?
Should I bring travellers cheques, credit/debit cards or cash to Cambodia?
Should I tip in Cambodia?
Are leeches a problem in Cambodia?
Are legal drugs cheap in Cambodia?
Do I need a prescription in Cambodia?
Do I need malarial medication in Cambodia?
HIV/AIDS in Cambodia
Is heatstroke a problem?
Is medical care cheap in Cambodia?
Is medical care in Cambodia good?
Is rabies a problem in Thailand?
What about dengue haemorrhagic fever in Cambodia?
What about schistosomiasis in Cambodia?
What general food and water precautions should be followed in Cambodia?
What general health advice can you offer for Cambodia?
What should be in a traveller's medical kit for travel in Cambodia?
Will I get diarrhoea in Cambodia?