When it comes to warming up, dynamic exercises are far superior to static stretching. Not only do they loosen things up without harming performance, but the right combination can also activate muscles and enhance performance.
Active Deep Squats
The deep bodyweight squat should already be part of your daily routine. What's even better than the deep squat, though, is the dynamic movements you can perform while in one. These movements will not only loosen up the three areas that are commonly tight (hips, knees, low-back), but they'll also give you the opportunity to zone in on the lats, scaps, and glutes.
The Cat Camel
This is a good introduction to how to move while in the deep squat, and it's spectacular for stretching the low back, firing up the scaps, and improving body awareness. To get more from the exercise, focus just as much on protracting and retracting your shoulder blades as you do on rounding and arching your lower back. Also, don't be afraid to bring the knees in during the camel (round) and push them out on the cat (arch) to really warm up the hip sockets.
Around the World
This is very useful for the external and internal rotators of the hip, which tend to have some residual kinks no matter how well you warm-up. This will also loosen up the knees by acquainting them with the extended ranges that may or may not be encountered in the upcoming lifting session. Bonus: They'll also give the lats and trunk a good stretch.