The important thing is to a) not overstuff them and b) keep the limit line to which you pack, so that when you roll the bag up there is enough room where the air can escape. There are also compression bags that work with a vacuum cleaner which work a little better. Ziplocs will do the trick, too, but won't compress quite as well. Aloksaks would certainly also work.
And remember to put those heavy items on the bottom of the case where the wheels are. The lower center of gravity makes for much better maneuvering.
Inside of boots is also good for fragile stuff. For example, I just transported a glass bottle of shoe cleaning fluid in a boot secured with a pair of socks. Worked great.
Knit stuff compresses much better than woven textiles. Down compresses better than fleece as a general rule.
Till