Positions
Whole bow shot is mostly about the motion. Nevertheless there are several places where we can characterise different techniques by their static positions, not by how they change. It is mostly about the way how we hold the bow, position of nocked arrow, and position of string hand when drawing the string. In this section I just prepare the grounds for the techniques themselves.
I will use following therms throughout the whole web. Bow hand (or front hand) is the hand that holds the bow - left for right-handers. String hand (or back hand) is the hand that draws the string - right for right-handers. Inner side of the bow or string is the one facing the bow hand - the left for right-hander when holding the bow vertically. Outer side of the bow or string is the one that is farther from the bow hand - right for right-hander.
How to stay, what stance should I shoot from
The question of stance is often overrated. To demonstrate that there is not just one perfect and ideal stance, I have put several photos of different archers in the gallery at the end of page. All of them are archers for who the archery was necessary for survival - be them hunters or warriors. Notice that every one stands in a different way, some of them are even kneeling (others - which is not in gallery - would sit on the horse), so we cannot talk about "stance" at all.
If you don't know what stance to stay in, there is some universal (and only) constant - stay with the bow leg forward (so the left one for right-handers). That is all for constants, and variability starts. You can stay in quite wide stance or narrow with legs near, or anything between. Someone likes to face target head-on, others turn hips to it (and others again something between). Somebody leans forward because he fells better the space around, others bring weight backwards so that they are as firm as rock when shooting. Someone stands proudly straight, others shrug as if they wanted to hide behind the bow. Nothing of this is bad! If you feel comfortably in the stance and you shoot well from it, then it is a good stance.
It is also neccessary to say that many historical archers count not choose their stance. For example the mongolian rider had to cover at least 180 degrees of angle from its "stance" (or rather "sit"). When he was followed by enemy, he just head to shoot to the back, and could not complain that he rather likes to shoot head-on. Scythes or Greek liked to kneel when shooting, probably to offer small target for enemy. For the same reason some native from south-americal jungle will rather shoot crouched behind bushes, because he knows what would happen if he stood up proudly to an ideal archery stance. And when any archer unexpectedly got to close contact with enemy, he had kto run and shoot while running, without possibility to stand in the right way.
If you want to make your archery more interesting, try to shoot from other the ideal positions. Many historical archers had to learn it, because they were often forced to it by circumstances. Try it too, it is interesting.