For a standard guitar string length I start with 2 mill compensation on the treble string and 4 mill on the bass. That's for a low action. If you like your action high then the compensation needs to be increased. Once you have a good working string length, write the compensation down. With something like +2.5 on one bridge foot or end and +5 on the other, you will will take all the future guesswork out of it.