My directions are for a right-handed pool shooter. For the two feet in my stance, I work to create basically a 60-degree angle between my feet to meet what I term the "60 degree rule of pool".
Settling the feet onto a 60-degree angle helps to ensure the shoulder of my shooting arm, my right arm, stays stable in place throughout the classic pool stroke, at least until after impact has been made upon the cue ball. Such arm stability helps make for a near pendulum movement of the shooting arm from the forearm down. I say "near" as there are number of factors that make the classic stroke somewhat less than a true pendulum movement for most players.
I point my left foot out, toes approximately toward the object ball I am aiming to hit with the cue ball, as I step forward. My right foot tends to flare out to the right to balance my weight, so that its toes run nearly perpendicular beneath the line of the cue stick along the shot line.
Drawing imaginary lines from my toes through my heels, the lines would intersect and form approximately a 30-degree angle. You will find some variation of my stance works for you (for example, placing your non-shooting side foot straight out rather than pointed toward the object ball), but do stand so that your shooting-side shoulder sits in place through much of your stroke--effortlessly via the placement of the feet. It's a winning position!
