We handled our's like CRAZY since they were 2-days old. Every morning and every night. We would hold them until they fell asleep and then sit and enjoy chicken-TV, watching the ones we weren't holding at the time.
They all come and stay by us when they are free-ranging, now. They'll come when I call "chick-chick-chick". They all LOVE, love, love belly rubs are bedtime. They purr and fluff all up and go to sleep.
Some are more willing to be picked-up and loved-up, then others. Some squawk like crazy - like we're goin' eat them - and then calm down and put up with the snuggling. One of our bantams thinks my daughter is her momma, so she is like having a pet dog. A couple of them fly up to my shoulder or head.
BUT, this our first ever experience with chickens, so I am no expert! We just couldn't keep our hands off of them, so they learned to tolerate it. BUT, but all of this being said...I CLOSELY monitored the handling. If they appeared to be stressin' out, we would put them down. We also spent a lot of time just watching them and being with them and NOT handling them. So, I guess it was just a lot of time with them overall and some very controlled, kind handling - all depending on their individual personalities and the feedback they gave us.