Mine are all tame, I agree with pretty much everything everyone has said.
Handle them (very gently- chicks are fragile) a lot as youngsters. Pay no attention to initial peeps of resenment they get over it fast.
Mostly my older ones do not like to be petted, but love to be gently scratched especially under the chin and on the back of the neck like they would preen each other. They beg to be held but mostly like to "roost " on my arms or knees if I am sitting.
Birds have birdbrains and forget you in a heartbeat. You have to continue to interact with them to keep them tame. It doesn't have to be much , but at least a few minutes several times a day. I remove the feed and water and lockup at night, visit and talk a few minutes, replace the food and water in the morning, and watch to see everyone gets a share. I also let them out to range for a while late afternoons and usually spend some of this time in the garden with them. I think without the continual extra handling they would be freindly and calm, but not walk over and jump up on your hand on command tame like they are now.
IMPORTANT NOTE: It is reasonable to expect to have a few tame/pet chickens but not reasonable to be loved by a large group. If you have 15 hens or something aim for a calm freindly group, and make special pets of the one or two that seek out your affection.
Handfeeding like all bribery has it's uses and limitations, when I have done a lot of it I have found I get pecked more. Now I use the hold and carry method more often. I use the call to feed to get them to come running in at dusk.