Wear and use proper gear for your sport, including helmets, pads, shoes, sunglasses, gloves and layered clothing where appropriate.
Understand the rules and follow them. They are in place for a reason.
Warm up slowly before activity. This is especially important in sports that require quick, dynamic movements, such as basketball, and soccer. This helps to increase heat throughout the body slowly and reduces the risk of tearing or straining muscles by increasing their ability to lengthen.
Take a 2-3 minute jog, to raise a light sweat before you stretch
Always use proper body mechanics in sports involving repetitive stress to the upper extremities. (tennis, baseball, golf).