Yes, there is a method. This would be much easier with a simple picture but here goes...First off you shoot through the diamonds on the rail not directly at a point on the cushion perpendicular to the diamond.
So draw an imaginary line through all the diamonds around the table creating a big rectangle. I will call this the diamond line.
To use a cross side bank as an example...(assuming that the object ball is off the rail at least six inches)...
1) Draw an imaginary perpendicular line through the object ball to the side rail that you are going to bank the ball off of and note where it intersects the diamond line.
2) Next draw an imaginary line from the center of one side pocket to the center of the opposite side pocket.
3) Lay a cue diagonally through the center of the object ball and through the center of the side pocket which is on the same rail that you are going to bank the ball off of.
4) Next make an X by laying a second cue from the center of the target side pocket to the point defined in step #1.
5) The 2 cues will intersect somewhere between the object ball and the target pocket. Draw an imaginary perpendicular line from that intersect point to diamond line on the banking rail. Put a piece of chalk at that point on the diamond line.
6) Hit your object ball "through" the piece of chalk.
If you can follow all that and make sense of it then bank shots should be cake. :wink:
That's enough geometry for one post.