Getting an angle by Robert Byrne
One of the keys to running balls is getting an angle. Not only must you make the first ball, you must get an angle on the next ball that permits you to get the third one. In other words, you must plan three shots ahead. If there is a cluster that must be broken, the task becomes getting an angle on a ball that can be used as a break ball. In diagram, the 6-7 must be separated. To do it, follow forward softly on the 4-ball, leaving the cueball in a position to carom onto the cluster while cutting the 5-ball into the corner. A good nine-ball player would spot the possibility at a glance even with five other balls on the table and might make the 1-, 2-, and 3-balls in a way that leaves the diagrammed position.