Immunizations

Check with your government's recommendations (or with the CDC or NHS even if you're not American or British), but I believe the only essential vaccinations are typhoid, tetanus and hepatitis.

Rabies is optional but may be recommended if you expect to be working with animals or visiting remote areas.

Similarly, anti-malarials are superfluous in the cities but may be recommended if you're spending time in the countryside or jungles. I've seen some people argue that the strains present in Cambodia are now resistant to all common anti-malarials, but I don't know if there's any truth in that. I lived without the rabies vaccine or anti-malarial treatment for > 18 months, and most expats don't bother.