It's really important to use a few quick drills before running to activate the right muscle groups especially if you're a beginner. This is in addition to stretching! Make sure you are slightly warm before doing these for example after a light jog.
A few of my favourites:
1. High skip - use a big leaping skip reaching into the air with the opposite arm to the leg you are lifting.
2. High knees - keep nice and upright with knees nice and high keeping the consistency.
3. Butt kicks - keep upright but with relaxed shoulders, flick your butt with your feet keeping the consistency and sharp movements.
4. Squats - use a deep squat steppong out to the side and rotate sidewise to keep a consistent movement - aim to do about 10 squats in a row.
Watch Jules, one of my clients, in action demonstrating the high knees and butt kicks