Uhm.... jeez, it's been ages since my hamster died. ^^;
Uhm...
make sure they always have water
give them a reasonable sized cage that you should probably clean out every other-every third day (letting it go for a week can be much more of a pain)
Un... don't give them baths
let them be in a cool, shady part of your room because they can be sensitive to heat
Never leave them unattended with other pets, even if they don't fuss when you're around
Ask you're local pet shop owner
And use google! D:<