Douglas Kehlenbrink of the International Double Reed Society (IDRS) writes that a warm up routine should address one major concern; the maximum results from training with a minimum of time spent. Doing a warm up routine the first time around is going to take more focus and determination because it is unfamiliar. Once a warm up routine is found, be sure to practice it daily instead of just using it once or twice. This will cut down on preparation time and still ensure a good warm up. Make warming up a habit.
Before you begin playing, you may want to consider literally warming up your hands. Bassoon requires a lot of finger movement, which can be difficult with cold hands. Running warm water over your hands is a great way to warm them up.
Make sure to take things slowly. Before you begin, take a moment to focus yourself on the task, and then begin playing long tones. Long tones are best done for no more than 10 minutes and should be done without vibrato. Be sure to use a metronome and play long tones at a rate that is challenging to you. You may do long tones in a melody that is familiar to you, or slowly on a scale. Move on to rhythmic exercise next, from simple to more complex. Rhythmic exercises can be done on scales or melodies.
Think of warming up as a pyramid, the bottom of the pyramid being the easier parts of the warm up and the top of the pyramid being more difficult practices. With your rhythmic practices complete, move on to slow scales, starting with the ones you already know or have recently learned. Move on to the harder scales and then practice arpeggios. Increase the speed as you acquire more finger memory for the scales and arpeggios, but be sure to go at a pace where you will not make frequent mistakes. Mistakes that are frequently repeated can become habit. You are now warmed up enough to play your pieces. Make sure you do this every time before you play.