Warm-Up for Flexibility
I have found that flexibility is one of the most important elements to developing ease of facility and efficiency of playing. I use a version of this warm-up every day, to calibrate and remind my lips where each partial lays, to promote ease of playing in the high register and flexible technique into the low.
This warm-up is gentle, and can be used for regular facility, to build range, or for rehab the day after heavy ensemble playing. You can download a PDF here: Horn Warm-up for Flexibility