Wiley Horne--So. Calif.
I have found two things useful, not that I always make the right call :

1. One is to study examples of the type thing you are making. Even there, you will be thrown back on your own judgment, because you will find differences between makers, or even the same maker. However studying the examples gives you a feel for the range of variation, and you will find yourself saying 'I like that better than this.' Same suggestion for the type of pull to be used, not merely its location.

2. Second thing is the viewing angle. A pull with some projection to it will look quite different if it is on a lower drawer, say, versus an upper drawer. For example, if you want a lower drawer to look like its pull is centered 1/8"above the drawer centerline, you may have to center the pull 1/4" or 3/8" above the drawer centerline to make it look right, because the downward viewing angle makes the pull appear lower.
As Hank Knight says, all of the above requires eyeballing + your own subjective judgment. And copying a piece you like the looks of takes a lot of risk out of the deal (duh).

Wiley