In a nutshell, I do dynamic stretches before excercise and static stretches afterwards. My static stretches are mostle aimed at adding flexibility to my ludicrously tight hamstrings. I'm finding that they are improving massively as a result. That is mostly running-related, but it does help me with my day-to-day work as well, which involves a lot of walking. My daily warmup routine is largely concerned with getting everything moving first thing on a morning. I reach up, I reach and bend to the side, I swing my arms around, lot's of stuff like that - mostly for my back. For my back AND my knees, I stand with my feet about shoulder width apart, then raise my arms above my head. Then I lean back as far as I can without risking toppling over backwards. Then I reach as far forwards as I can, while at the same time squatting as deeply as I can. (Normally that is a full squat, but when I have experienced knee pain in the past I have only squatted as deep as was comfortable.) I repeat that about ten times, and it seems to keep my knees and my back in reasonably good shape, while at the same time getting my thighs warmed up first thing on a morning, and getting my circulation going. I follow that by spiralling my hands several times in both directions from four different arm positions. (It's a variation on a chi gung excercise from Taiji class.) I find that doing that keeps my knuckles free from arthritic pain in the winter. Then I raise my thighs to ninety degress (one leg at a time!) and rotate my ankle several times in one direction, then several times the other way. I would never practise my form on a morning until I had run through my warm-up routine first.