You wouldn’t put your shoes on before your socks, so why would you modify your nut slots before adjusting your trussrod? When you approach problems with your guitar, it always helps to have a working plan. This is how I approach setting up a guitar.
More than likely, if you’re in the market for a setup, you are either trying to make your guitar feel better, or are dealing with a problem like buzzing. Let’s say you are looking for the lowest action with the least amount of buzz. I always start with the strings. If there is a kink in the string, it could cause a mysterious isolated buzz, or play out of tune, or just sound bad. Starting off with new strings can never hurt.
Tech-savvy guitarists might take out rulers and gauges and go to town, but not everyone is that guy. Try following these steps—which are about the same whether your action is too low or too high.
• Play the high-E string starting at the 12th fret and going up to the highest fret. Adjust the height of the string at the saddle as low as you can while still having it ring as clear as you need, making sure you still have the amount of bending you require. You will find a small adjustment will add more to your clean bending than you may think, so go slow.
• Do the same thing with the low-E string. Remember, you can always go back and undo whatever adjustments you make. I will often err on the low side, hoping the amp will hide some buzzing in exchange for lower action.
• Tighten or loosen the trussrod until frets 1 through 7 play cleanly. The tighter the trussrod, the more buzz you will get because you’re back-bowing the neck. I usually start by checking the low-E, as that is the toughest one to play cleanly. I always encourage adjusting too far in either direction—too clean and too buzzy—so you can see what the extremes do. Again, you can always go back. Reminder: Do not think about what the open strings are doing just yet.
• The nut is a little tougher to adjust on the fly. After you get the trussrod where you want it, the open string height should be as low as possible over the first fret with little or no buzzing, depending on how you play. The tricky part is, if you’re filing the nut slots lower, you won’t really know where to stop until you go too far and it’s buzzing. Two important things: Adjust your trussrod so your neck is as straight as you think you may ever have it before cutting nut slots, and do not adjust the trussrod or bridge height to make the open strings buzz less. That is solely a nut-height issue, and you will sacrifice the rest of the guitar’s playability by doing that.
• You may want to take notes to keep track of what you are doing so you can go back if you don’t like what you have done.
These adjustments are based on string buzz and feel. I like to say that most guitars will not defy physics and will buzz. If you are going for low action, leave a little buzz in your adjustments, you can always dial it out and see if the enjoyment of the low action is worth it. If you want higher and cleaner action, you can dial that in as well between the lower and upper part of the neck. Once you do this a few times you’ll see how simple these adjustments are, and I will be out of work!