Tea is my practice steroid.
I live in a basement suite, it gets cold often, frozen fingers are the worst. Tea keeps me warm, has some caffine to keep me buzzin', is healthy, and doesn't rot my gut like coffee does.
My back is usually stiff after work, and sometimes I get home a little on the tired side... I have a nap, laying on my back to get it relaxed, listening to whatever music tickles me to get motivated.
I figure that a persons back should be in fine shape from standing/sitting upright all day, every day. Good posture is the best I can think of to minimize the work your back muscles have to do.
I don't really have any routine stretch for when my back gets stiff. I just twist and move around however it feels good, or as I said earlier, lie down flat on my back... Lying down I can feel how tense and arched my lower back is, and as it begins to unwind and relax.