First, don't be afraid of doing it. Traffic isn't half as bad as indicated in several travel guides. If you are brave enough to ride a bicycle in Germany, through German cities you will not have and problem over here. All the major roads are paved but you always have to watch out for potholes. Actually in some parts roads seem to consist more of potholes than asphalt.
Officially you drive on the right hand side here in Cambodia but if it is more convenient to you to drive on the left hand side don't hesitate to do so. Cambodians do it all the time.
On our first day of our journey we learned: when the rainy season is over it may rain anytime! And it does. As you will be soaking wet with sweat all the time anyway a nice tropical downpour will not add much humidity to your clothes or skin.
You can easily refill your loss of water. Purified water is offered everywhere and you won't go hungry either. All along the roadside food stalls offer fresh fruit like melons, pineapple, bananas, mango etc., grilled meat ( better take a close look, it might be bat or rat, but mostly it is chicken), sweet sticky rice and so on. If you are more of an adventurous type you may try pickled red ants with maggots.
Of course you can stick to the traveller's rule: cook it, peel it or leave it but in doing so you will miss a lot of delicious things like the wonderful tomato salad or the vegetable pickles ( without ants).
In Siem Reap and Phnom Penh you will find posh restaurants, cafés and bars serving food from all over the world and traditional Khmer food like Amok or Loc lac. Amok is a sort of stew with fish or chicken in a slightly spicy sauce with coconut milk, garlic and lemongrass, absolutely delicious. Loc lac is a beef salad its quality depending on the age of the cow😉. Outside Siem Reap or Phnom Penh you better start looking for a place to dine before 6 pm. 8 o'clock at the latest every food stall, restaurant or shop will close but you will get breakfast as early as 6 am.
Accommodation is plenty even in non tourist areas. From outside guesthouses and hotels often look like elegant five star european hotels, inside you will probably have to cope with smelly bathrooms, dripping taps and smudgy walls. But what can you exspect for $ 12 or less a night?
In Siem Reap and Phnom Penh you will get along with English but in other areas English vocabulary is limited to "hello", "what's your name" and "bye bye". So learning a few Khmer words might be quite helpful. Especially numbers so you will know prices of food or goods and you will be able to bargain.
A real nuisance here as in many other countries of the world is the garbage. Awareness for environmental issues is not very common. Riverbanks and roadsides are littered with plastic bottles, bags, shitty nappies and so on. Even temple areas often look more like a landfill than holy ground and I am not sure if the word sewage system even exists in the Khmer language. So while travelling along simply ignore it and enjoy the many ponds filled with blossoming lotus and water lillies.
Cambodia may not offer as many cultural highlights (except for Angkor Wat) or breathtaking landscapes as some other Asian countries but you will certainly enjoy the relaxed atmosphere and the genuinely friendly people. Wherever you go you will be greeted by waving hands, a broad smile and a cheerful hello. So have a wonderful journey!