I've never had a warm up routine, I just play whatever riffs or solos I happen to be working on at the time at a slightly slower pace, then after about 15 mins I up the anti and let them rip. I find this helps me to nail solos faster because I'm warming up by playing what I want to play rather than a load of chromatic exercises which get boring after a few years! Either that or just writing a new part is warm up enough for me - I don't get much time to play at all these days so I try to adopt the 'shortest distance between two points is a straight line approach' to get the most out of my sessions (usually at 1am in between babies screaming for bottles). If I'm playing a small difficult part with an unusual pattern I might play it up and down over the entire fretboard in a scalar format over and over but that is usually just to get the rhythm and pattern/co-ordination into my head (it does help to play the part faster and cleaner too).