The two E strings are the same. The open strings and the 12th fret are the same. That gives you two points of reference vertically and horizontally.
Octaves from the E and A strings are two strings over and two frets up. Octaves from the D and G strings are two strings over and three frets up.
B E A D G – B E A D G – B E A D G
This pattern repeats across the strings over and over.
It’s the open strings – E A D G B E.
Three frets up on the low E string is G. So there’s a B sitting on the next string. B is always one fret down from G. B is at the second fret.
One string over from B is E.
One string over from E is A.
One string over from A is D, but D is on the B string so It’s going to be one fret up.
So Every time you get to the B note, it’s one fret down. Every time you get to the B string the note you’re looking for is one fret up.
One string over from D is G.
on the open strings and the 12th fret, B is the note on the B string, so the one fret up and one fret down cancel each other out.
At the 5th fret you start with A.
D is one string over…
That’s as simple as the fingerboard gets. The rest is just brute force memorization.
The way it’s going to stick is by using it.