Nap Help 101

This post is for all of the moms that have mastered the art of getting their children to nap (consistently). Our little 7-month-old, Charlie, is a great baby; however, he has an aversion to naps during the day. Any advice on getting him to nap consistently? He usually will take a 45 minute nap in the mornings...except for this morning when I let him cry for 30 minutes. In the afternoon, though, he might snooze for 30 minutes. This mama is just dreaming of a consistent hour-long (or longer) nap for him, so she can get some things done. Well, what do you know, he is crying now...from a cat nap. I've got to run, but would love any tips that people might have.