Ziploc bags work well as do silnylon stuff sacks. I am partial to the stuff sacks they are quieter when packing and I find that by using stuff sacks that are just big enough, I can compress stuff a lot better than with ziplocs. The noise of the ziplocs became an issue for me because I am almost always the first one awake and on the road and I didn't like waking my sleeping friends with the noise of packing the bags.