This is for tips and experiences. Despite knowing full well that I should warm up before practice, I've developed tendinitis. (It affects my ring finger on my left hand. It "sticks" in a bent position, and my forearm aches). It's a bugger. It means I can't play for I'm not sure how long. I'm using ice packs and generally trying to rest my left hand. Anyway, here's what I should have done: stretching exercises. starting off scales and arps routine slowly before building up speed (not that I'm a shredder). My normal routine is to go through the scales and arps in all the keys (round the cycle of fifths) in the 5 'caged' positions (this is guitar jargon - it's to do with how the fretboard works on a standard-tuned guitar) plus sometimes the 3-octave scales available from E as far as A. I go at roughly 120 - 152 bpm (two notes per beat). So not metal madness by any means. Anyway, it seems that despite having done it for years, you can still bugger up your tendons if you're not careful.