Always be sure to complete a dynamic warm-up before starting your workout!
Warming up not only maximizes your workout, but it allows you to work at a harder pace, and decreases your chance of injury.
Dynamic Warm Up exercises should always be moving, not static stretching. Static stretches should be reserved for your post-workout cool down.
Below are some quick warm-up and cool-down videos that you can do before any of the workouts on this site.
Warm Up Videos:
Cool Down Videos: