Before any practice or playing, do some warmup/stretching exercises.
In a warm-up, focus on the motion. Make it fluid and let it feel good. Do not hold position nor test your limits.
Jojo Mayer hand clapping:
This can be combined with feet warm-up, playing the feet on 8th notes with heel down.
Stretch your arms in front, holding two sticks. Bend your wrists down and up continuously.
Stretch your arm to the side, holding two sticks, extended (not parallel). Rotate them like a propeller in one direction, than other.
Half-Pretzel is a variation of the Pretzel exercise where only one arm is stretched. This is done by having one hand pointing up and the other down in the initial position.
The arm with the hand pointing up is the one being stretched. This one rotates.
The arm with the hand pointing down stays in the same position.
This is an extension of “the Pretzel”. After Pretzel stretch, lift your arms up vertically, then bow the elbows and put the sticks behind the head. Return to the initial position by doing the same motion in reverse. Repeat for 9 times. The last time keep the hands in position for ~10 seconds.
Another good stretch/warm-up tool is to just shake fingers, wrists, arms and shoulders.
For more exercises, see Exercises. Exercises without sticks are also suitable as warmups.
It is useful to warm-up, or generally exercise, the lower arm rotation. These muscles are used for better stick control and precise strikes. Try to rotate slowly and as much as you can.
This is similar to the Propeller warm-up exercise above. In the Propeller exercise, the whole arm is being rotated. Here we rotate only the lower-arm. This can be achieved by holding arms next to your body, in the playing position, bent in the elbow so that only the lower arm is in horizontal position.
Stretch the muscles after playing if they are stiff. See “Stretches for Drummers” link in the References.
Put your legs in a natural position. Lift the toes as high as you can, keeping the heel on the flor. Do quick taps, keeping the feet up. Play 8th notes (while hands do 16th notes). A good starting tempo would be 80bpm.