STRONGLY recommend reading articles at the Trainers site and hooking up with one if you can. They will and DO teach more than just basic ACM, air combat maneuvers.
Silly as it sounds, it's important to not let them get behind you as you then have to hope or force them to make a mistake, which can be difficult to say the least. You really need to work on SA, situational awareness or knowing whats going on around you at all times, and maneuver against the enemy long before they do saddle up on your six.