There are some arguments about whether or not stretching before &/or after exercise reduces injury risk. Studies are mixed, but they all tend to agree that stretching can decrease general muscle soreness & improve overall flexibility.
Here a few tips for stretching:
• Static stretching is best post exercise, incorporated into your cool-down, & should include muscles predominantly used during the exercise.
• Dynamic stretching is likely the best form of stretching before exercise. That is, stretching through range of movement, rather than holding the stretch.
• You should aim to hold each stretch for 20-30seconds.
• To improve overall flexibility, stretching can be done as a stand-alone thing. A minimum of twice per week has been shown to improve muscle flexibility.
If, however, you are unsure about anything to do with stretching, ask your friendly physio!