After removing the nut, I use a very small chisel to remove the surface glue. The glue residue left in the wood is removed with a fine file while leveling the nut slot bottom...
With the nut blank roughed in, I mark the distance in from the fretboard edges for both E strings. Using a graduated spacing rule, I match the outside marks for the E strings and mark the remaing 4 string slots...
I use a fine razor saw to start the string slots. I find I can keep better control and get the most accurate, graduated spacing from the small strings to the larger strings...
Working the nut slot files from the headstock side of the nut, toward the fretboard. I make sure the string slot take off point to the saddle stays higher than the back. This avoids the buzzing sound you hear when a string is played open...