Hamsters are solitary animals. You will need to move slowly when working with your hamster. They are skittish and have poor eyesite. They may bite you if you surprise them. They are extremely quick and they will jump from very high places because they don't have any concept of height.
Hamsters are nocturnal so think carefully before placing their cages.
I can remember many nights that the little guys woke me up by running in their exercise wheel. Your hamsters cage will need to be kept clean and dry at all times so you will have to be willing to clean the cage thoroughly twice a week. Young children must be supervised around them at all times. When choosing a hamster, keep in mind that the females tend to get cranky with age. If you choose a female hamster, make sure she was kept with only females at the pet store.