There are two clear options available for traveler and people who want to know how to go to Cambodia and it depends upon their current location and also their finances:
1) First option is via Tour Bus.
Especially for people already in South East Asia (e.g. Thailand, Laos or Vietnam) who like the simple option to cross the border to go into Cambodia since this is a cheap option and favored highly by the backpacking community or those on a budget. However this is the longer option and depending on the route taken it can be uncomfortable for some legs of the journey. Night bus is not recommended under any option due to the high level of accidents at night.