Rest day. Follow the sequence outlined here. Alternatively, attend a basic, gentle, or restorative yoga class. It's useful to study with a live teacher periodically, to ensure you're practicing the poses safely and with good alignment.
After a harder workout. Hold each pose five breaths or so.
On a lighter workout day. Move through the exercises listed here. Hold each of the poses for five breaths or more, until you feel even side to side.
After a harder workout. Hold the backbends ten to fifteen breaths (or more); hold the lunges at least five breaths each; hold the reclining twists at least ten breaths each.
On a lighter workout day. Move through the routine, following your breath in both dynamic and static poses. Repeat three to five complete rounds of moon salutations (starting and finishing at the left side of your mat), and hold each of the hip and leg stretches at least five breaths.
After shorter weekend workout. Move through these poses, holding each ten breaths or more. Prop your hips from below if you feel strain in your back.
Later in the day of your longest workout of the week, when you're clean, warm, and fed, enjoy these poses. Hold each for as long as you like, at least five minutes, with special attention to resting with your legs up the wall.