If future post it in one forum.
How you overshoot enemy planes depends on your plane, your gear, your speed, your alt, enemy plane, enemy speed, enemy alt, and general situation around you. Best tactics to learn anything is to keep your film on, and check films after all your sorties. Now you can even jump to enemy plane, and watch how he does it.
It is also 2 kind of overshoots, the one, which just save your life (defensive) and one, which put you in a good position for attack (aggressive). Agressive overshoots are usually more risky, and require much more expirience to be effective.
For you, while you are still a newbie, I suggest following this: if you slow, your enemy is fast, you have some alt -- split S. Very easy one, and will prolong your life for some time, when may be friendlies will come, or your enemy will make some mistake, like following you at full speed and will auger... This one easy to master and quite effective.
If you are in a better turner plane, you are low, enemy plane is about same speed -- turn hard and watch him. If he follows, keep turning. If he breaks. it is up to situation, you can get his 6, or flight straight waiting for him to make another pass.
Remember, in any case, it is important to chose a correct time when to start your defensive moves. For defensive overshoots you need to start them while he just entered the effective range for his guns, when he starts following the pipe on you, lining for a shoot. In this case more chances that he will follow your move, and this will give you a chance to turn a table.
