Chickens tend to enjoy their spa day.  If they're a bit flighty at first, they quickly settle down. 
I use 3 small - medium totes, and fill with warm water (not too warm) that the bird can sit down, and the water is half way up the bird, but doesn't go over it's back.  Add a bit of Dawn.  Blue is best.  Make it like you would for washing dishes.  In the second tote, add a tablespoon of white vinegar to the water.  The third is to be plain water.  Now set your bird in the tote, keeping your hand on it's back.  In a minute, it will settle down.  Most of mine will lay down in the water on their own, but I have a couple that after they settle down, I give a gentle push on their back, then they lay down.  Let it soak in the soapy water for about 10 minutes, then begin rubbing the feathers in the soiled areas.  Clean everywhere, but the head, and be careful NOT to get soap into it's eyes.  When it's clean, lift the bird, and transfer it to the second tote, with the vinegar water.  Rinse all over, except the head, with the vinegar water.  You can use a plastic cup to help.  Now, move it into the plain rinse water.  Be sure to rinse thoroughly.  Wrap in a towel. 
Now that it's calm, and wrapped in a towel, get a washrag, and plain warm water, to clean it's head, and face area.  Be gentle.  Now, move to the feet.  This is a great time to trim spurs, and toenails.
Make sure they're dry before putting them back out.  Careful, if you use a blow dryer, so as not to overheat the bird.