Work your hams before your quads too.
1. Standing leg curls.
2. Laying leg curls.
3. Stiff-legged DLs.
Then start your quad workout. A lot of the time when you hit quads first, your hams get a little stress, and ultimately, by the time you start direct work on them, they're already too tired out.
This applies to those of you who hit quads/hams on the same day.