For alternate tunings: typically for every 1/2 step that you tune down, you need to increase your string gauge from the standard set, or gauge that you currently use. For example, if you currently use 9's and your guitar is properly set up, you would switch to 10's to tune to E flat. Increasing your string gauge will also increase pressure at the nut, so the nut slots need to be cut wider. This is best done using a file. It will change the tension of the neck, so the trussrod will need adjustment, it will also change the intonation (how to adjust intonation is discussed in another FAQ).