What are the best stretches to do?
Any movements that challenge you to re-imagine what you can do, and how you do it. How fast or slow, big or small, up or down, Left or Right, forward or backward, simple or complex. Instead of thinking of individual muscles, which is not how your brain organizes you for action, practice variations of the movements that are required in your sport.
For example, the hamstring muscles have a medial (inside) and lateral (outside) component, and pass over the hip and knee joints, so practicing movements that involve both joints, and multiple angles is essential. In addition, the hamstring muscles are mostly engaged while you are moving your pelvis over your feet in running or dodging, so practicing stretches of the hamstring muscles with a stationary pelvis does not closely model how you will engage them during your activity. The pelvis is the center of power, so engaging this area in combination with the lower and upper extremities is key. In addition, the eyes are engaged during all these activities, and where they go, the spine will follow. Bringing in variations of eye movements will add layers of complexity, and demand balance subtleties that more closely resemble game conditions.
A huge bonus comes with preparing in this way. Rather than creating a false sense of 'me' doing things to 'my body,' and then trying to put yourself back together for a game situation, you are actually practicing being 'in the Zone,' all the time.
Sample: This W/E, I added a pre-game warm up for the 6th Grade Basketball team I'm working with. Moving from one base-line to the other and back, I asked them to imagine that they were ducking under a long low table, then reaching up to run their hands along a line of feathers, then dodging a huge rock to the left, then another to the right, then leaping over 2 deep puddles of water. Then doing the same while dribbling a ball. This covers moving while in a low position for defense, lengthening for jump shots, cross-overs, and the steps they take for lay ups, while engaging them in the present moment of an imagined situation, and laughter too! Fun and learning go hand in hand.
Next time: How soon after an injury can I return to my sport or activity?