I put a trash compactor bag in my bag and then just jam my sleeping bag into that. I just jam it in randomly... I don't roll it or fold it first. I jam it down as much as I can then add my pillow, down jacket and any extra clothes I might have. I push it all down as much as I can and fold down the top of the trash compactor bag. I then add everything else on top. I pack food on the very top... because I want to eat during the day. Also, if I have things like crackers or chips I don't want them getting crushed.

edit: I want to add that I started doing this based on advice here and around the net. the idea being that the stuff sack is awkward to pack. Doing it this way, the equipment on top compresses the sleeping bag into a natural shape around your other equipment. I think that is true, but the final compression is much smaller for a just the right size stuff sack. With a stuff sack you have more dead space, but I am not convinced you have less room. I think both ways work out to be about the same amount of taken up space.