I use Space Bags, which I bought at Meijer. You can get them at other retail outlets and order them from the TV ads, too. They compress your clothes and add more space in the luggage. You can also use the big ones to store blankets and other seasonal items. Those you have to have a vacuum cleaner to suck out the air. I use the smaller ones and just sit on them to force out the air before zipping them shut.
You can use space Bags or regular zipper bags to put your cameras and film for easy access at airport checkpoints.