I train agility, explosiveness/power, and foot speed before I focus on actual speed training. Learning those different aspects of training will make speed training easier, allowing to focus on the mechanics of speed training.
Agility, foot speed, and power can be taught by using simple exercises such as toe taps, speed skaters, explosive skips, bounding, and other Calisthenics type exercises. Two of my favorite tools are the speed/agility ladder and dot mat. These tools enable you to train agility, foot speed and power, while making it fun and challenging for your client.
Power and speed can be developed by performing plyometrics, hills, and as Larue said deceleration. A form of deceleration training that I use is decline sprints. Decline sprints not only help with learning deceleration, but also help increase speed.