Copy and paste this link into your browser, and open the pdf file when the option comes up:
posc.tamu.edu/library/extpublications/b6092.pdf
It's an excellent guide to incubation and hatching from the University of Texas, and it's got great info about how best to store hatching eggs to maximise their hatchability. If you're only keeping eggs up to 7 days or so, you don't need to worry too much about storage conditions as long as they're kept somewhere relatively cool and clean. Longer than 7 days storage time, how you keep them becomes more important the longer you want to store them.
As part of an experiment, I've stored eggs for over 3 weeks and had good hatch rates with them. If I wasn't running a specific experiment on egg storage, I'd be setting the freshest eggs possible, and would use eggs that were at the most 10 days old.