3 Easy Steps
1. Memorize the name of each open string – EADGBE
2. Memorize the musical alphabet -ABCDEFG
All the letters in the musical alphabet are a whole step apart (2 frets) except
For (B to C) and (E to F) which are 1/2 step apart (1 fret).
3. Memorize sharps ♯ and flats ♭.
Sharps and are the notes between the letters of the alphabet.
Check out the chart I made below.
I hope this helps.