This is what I did and appears to have worked so far.
Monitors are naturally inquisitive animals and are always investigating things. I figured I would let my water monitor come to me, so I never grabbed it or touched it without permission. I spent time just feeding it and letting it get comfortable with the new surroundings. Then I began to hold my hand into the cage, talk in a normal tone, and would just sit there patiently. Patience is the key word there.
Eventually she started to come around and investigate my still hand. As her comfort level appeared to rise somewhat, she began to walk out on to my hand. Now I just open the cage and she comes right out and tries to walk up my arm. But when I have the monitor out of the cage, she is always trying to get places and investigate more. I haven't had her just lay there and do nothing in my lap, but she hasn't ever bitten me and doesn't run away when I come near. She seems too inquisitive to sit still for very long though.
Anyway, I have been very satisfied thus far with how it worked out, so best of luck to you. Remember, be patient and don't force yourself on your monitor. They tend not to forget.