Being a hard target will make you less appealing to criminal elements in Cambodia, so it’s worth doing. Never flash jewelry or money, especially in larger cities or tourist places.
Leave your valuables at home or in your hotel safe, and only take a photograph of your passport with you. Fancy clothes with brand labels, gold jewelry, and expensive cell phones can put a target on your back.
If you must use your cell phone on the road for directions, duck into a restaurant or well-lit place to look at it. Avoid walking with your cell phone in your hand.