This main seem lame and boring but this is essential to mastering the guitar.
MEMORIZE EACH NOTE:

Helpful hint:
Start out with one note say E and work on it until you know where that note is all over thr fretboard.  Play it on the guitar and mentally play it.

Low E: 0 12
A: 2 14
D: 7 19
G: 9 21
B: 5 17
E: 0 12

etc
This will improve your playing and your ear training

Thanks
Jack