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No matter how long you are running, you never want to start at your fastest pace. You muscles need time to warm up and gain elasticity to be effective and avoid injury. Start at a pace roughly 40-50% your running speed to begin your warm-up. These are exaggerated runs that warm up specific muscles and help your legs prepare for a full range of motion. Do each of these "dynamic stretches" for at least a minute, or try skipping as well. High Knees: With every step, lift each knee up to hip height. Butt Kicks: Exaggerate lifting your back leg so your heel comes up and taps your buttocks. Shuffle Step: Turn sideways and move horizontally for 3-4 steps. Pivot on your front foot and face the other direction, shuffling for 3-4 steps before alternating again. These often forgotten muscles need to be loose for a smooth running motion. Take some time to do "hip openers and closers" to get ready. Hip Openers: Walking laterally (side to side), lift your front knee up to hip height and then slowly arc it out to the side, turning you the other direction. Repeat with the other foot. Hip Closers: Walking laterally, pick up your back leg and arc it in front of your body. Pivot on your balancing foot so that you face the other direction and repeat. . Your thighs and butt muscles are essential for running, especially up hill. Get them firing with some lunges: Step forward with one foot, bending 90 degrees at the knee. Rest on the toes of your back foot. Drop your hips down towards the ground, keeping your front knee bent at 90. Keep your back straight as your drop. Pick up your back foot and step forward with it, repeating on the other side of your body. Repeat 10-15 times on each side. Exhaling as you bend, bend with a curved back and reach for the ground. Return to standing position and then bend backward, thrusting your stomach out. Perform several twists to either side, turning from your hips, and then bend sideways each way while keeping your feet in place. These stretches loosen muscles and joints in your spine to prepare it for running. Static stretching is the classic "grab and hold for 10 seconds" stretch. Many studies show that static stretching can actually decrease by performance by tearing muscle fibers. After warming up, limit yourself to a few light 10-15 second stretches on any muscles that are still sore. A stretch should never hurt -- so don't push yourself thinking that you are getting a "better" stretch.
Jog for 5-10 minutes. Mix high knees, butt kicks, and shuffling into your warm-up run. Warm up you hip muscles. Do lunges to prepare your quads and glutes Bend and flex to warm up joints and tendons. Avoid vigorous static stretching.