I use a 9-LED flashlight, and make sure the batteries have a fresh re-charge. (obviously, I'm using rechargable batteries. But brand new regular batteries will work fine.)
I just use my hand to circle the flashlight and form sort of a seal against the egg. I shine the light up through the bottom of the egg, then down through the air cell. I don't turn the eggs, but move the light.
I only candle at day 10 or so, and again day 18 when I remove the turner. All my eggs are shades of brown and green, except one hen lays cream colored. All eggs are candled the same way, regardless of breed, but in very dark eggs, and a lot of the green ones, sometimes you can't see much. A good, bright light helps, but sometimes you just won't see a lot. Most brown eggs I can see the veining and a moving embryo at day 10. Day 18 they're just mostly dark, sometimes I can see veining at the edge of the air cell.
I candle at night, when the room will be dark. You need a darkened room, though it doesn't have to be pitch black. A little ambient light's ok, as long as you can still see into the egg well enough.
