I've always found that with taming any rodent, using the back of your hand with your fingers closed is the best start. Offering them a hand in this position makes them feel safer, as if they jump on it you cannot suddenly grasp them and hoist them away. They'll get used to your scent and the presence of your hand in the cage. In time, you will be able to turn your hand over and practice lifting them a little off the ground.

Rodents are also naturally inquisitive, so I suppose basically, make being with you interesting! The obvious thing to use is treats, but you can experiment a little with things to chew and maybe even toys. The day that you have a pet that actually wants to come out to see you rather than you having to disturb it is the day it's truly tamed.