The following method is used by a vet nurse to tame semi-feral kittens. She has great results with it.
When I give them their food, I sit on the floor with the kittens’ food bowls on my knee. I do not look at them but sit patiently until the kittens are hungry enough to approach their dishes, and eventually hunger gets the better of them.I do this for a few weeks, eventually the kittens sit on my knee eating their food and over time I am able to stroke them gently while they are eating.Eventually they stay on my knee for a cuddle when they have finished eating.
I spend a lot of my time at their level, playing with them whilst lying on my tummy; this seems to put them at ease.I try my best not to make too much contact and let them approach me which works wonders.
When they are sleeping and relaxed I approach them and gently stroke them with a feather, and eventually with my hand.
I also find that putting cat milk on my fingers and letting them approach to lick it off works wonders.