I know that I am still new to the whole world of snakes. But just with the little bit I know I have to kind of call those that say this out. Feed your snake once a week, and handle it three times a week (or more, whatever). Through repetition, if the snake sees your hand more by being held, than being fed it is likely to assume that it is going to be handled when it sees your hand.
Or you could never let it see your hand when you go to feed it.