Numbering Quadrants:
Numbering each quadrant of the object ball and the cue ball depends where is the pocket (where one wants to sink an object ball into) in view (left or right) of a virtual line going straight through an object ball and the cue ball as shown in Figure 6 below.
Fig. 6
As shown in Figure 6 above, there are two
situations where the pocket you want to sink an object ball is either
on left of the virtual line passing through straight between the object
ball and the cue ball (Situation A) or on right of the virtual line
(Situation B). In case of Situation A, you start numbering from
left to right 
and
in case of Situation B, you start numbering from right to left 
.
Though the Figure 6 shows in relation to short rails, similarly one can apply a similar situation in relation to long rails. You may want to go on a pool table and understand these two situations with different shots. I hope the Figure 6 is clear to understand two different situations with imagination that corners are pockets on a pool table.
As with any aiming system, this system is not full proof. It will require some time, patience, and practice to understand and get better day by day in pocketing balls. One important thing to remember the detailed explanation of the system below is regard to a shot where the cue ball is at least a foot or more away. If a shot is less than a foot away, there will be required some adjustments. For example, a thick shot may become a thin shot and a thin shot may become a thinner shot. Sometimes you may have to line up your starting aim close to the edge of cue ball or little far from center. I don’t mean to confuse you but just for your information so you don’t get frustrated for a close up shot. Trust me this is going to improve your aiming and you will enjoy the game because now you will find how easy it is to pocket a ball.
I have prepared a video to explain further hope it will help but sorry for a poor quality as I am not a good cameraman.