Here's what I learned. I'm just a newbie myself! I got my first flock this year.
There are a couple that were completely skittish and apparently always will be.
The others... it helped to not pick them up every time I went to check on them. I would try to check for pasty butt by sight instead of picking them up. What I did was to just let my arm dangle there in the brooder as kind of a "perch" for them to jump up onto.
After a couple of minutes they would get curious about my arm and hand, and maybe peck at it a little. After a few days of doing this about 1-2 times a day (not picking them up unless absolutely necessary) the first one jumped up on my arm. I was VERY careful not to pet her or scare her and just let her jump on and off my arm.
Then, after a few days of the first one doing the arm jumping.... when she now jumped on my arm, I would slowly move my arm up to my eye level so she could see my face - talk to her a little and then gently move my arm back down and let her jump off. I wouldn't try to handle her.
Over the next week, the others, seeing that she could do this safely - started following her lead and then wanting to jump on my arm too. I would repeat the above with each bird as they became brave enough to jump onto my arm.
After a couple of weeks of this arm training - then I would start to bring my arm to my chest with the bird on it and then use my other hand to pet it. Each one would resist at first, but I would force the issue for no longer than a minute with whoever would climb on my arm - and then put each one back gently by lowering my arm back down. Then, they eventually learned to like the petting.
I noticed that when they were about 3-4 weeks old - each bird one by one started to "notice" me. They would look at me when I walked into the room and kind of eye me up and trying to figure out what I was. Their curiosity about me grew substantially. The more reluctant ones started to jump on my arm at that age.
I still have a couple that won't go near me, but now that they are 6.5 weeks old and in their coop - most of them come running to me when I go to the coop and run. I will park a chair in the run and sit there - and most of them will jump up to me and want to be petted. The ones higher up on the pecking order always get first dibs and then when they are done the lower pecking order hens get their turn. I'll have six birds on me at once (shoulders and lap).
I'm thinking I need to get some safety glasses because I'm worried about eye pecking