The guitar fretboard lends itself well to visual shapes and patterns. The circle of 5ths is no exception. While we can’t see it as an actual circle, we can see a pattern for sharps and a pattern for flats that connect to each other.
For Sharps start on C at the 3rd fret of the A string and plot out the 5ths like this:
For flats, start on C at the 15th fret of the A string and plot out 4ths like this:
Notice that the F♯ and G♭ overlap at the 9th fret of the A string.
Using this visual pattern, you can quickly determine the correct number of sharps or flats for any given key. Using the Father Charles mnemonic, you can quickly determine which notes in the key signature are sharp or flat. Once you’ve used these tools enough, you ‘ll find you quickly memorize the spelling of each key.