the first thing Im sure greg and renee and most everyone will say is practice, practice practice
other then that, it comes down to a few basics...
slowing down the shutter to let more light in, (but if you slow it down too much things will look blurry froim your moving the camera)
the other thing is ISO setting...
try to find the iso setting and make it as big as possible.. when lookiing for new cameras, try to find one that has uber high iso, or at leasty as high as you can afford
then find the MACRO mode for your camera... on my camera, it is a button near the shutter/clicker button. the icon is a FLOWER
that will let the camera take picture closer to tha camera without blurrying
my camera has two macro settings... i usually use the middle setting...
other then that, you can play with white balance settings... usually good to set it to the coud setting...
thgen get a tripod.... due tot he slow shutter, a tripod will keep the camera steady
good luck