First, draw a plumb line to make sure the hat channels will be spaced properly for the size of drywall and insulation you're using. The hat channel (Image 1) should be attached to the wall using concrete nails and concrete-nail gun (Images 2 and 3). Drive three concrete nails, spaced at even intervals, through each side of each hat channel.
Add some rigid board insulation between the hat channels. It won't insulate a lot, but it will provide some reflective heat. Use a thick zigzag bead of heavy-duty adhesive (Image 1) to glue on the insulation (Image 2). Cut around any electrical or plumbing you come across.
If you're working with a ceiling, start there and work your way down to the walls. Begin by marking plumb lines on the drywall that correspond to the hat channels below. Have a friend hold the drywall in place, and then screw it into the hat channels with an electric screw gun. Once all the drywall has been attached, it's ready for finishing.