There are usually about 21 frets on an acoustic guitar and since there are six strings that means that there are going to be around 126 notes. That’s a lot to memorize, right?! Well don’t worry. The trick is memorizing just a few key points and then using them for reference.
Start with the 6th string and just make sure you really know where to find G (3rd Fret), A (5th fret) and B (7th fret).
Once you have that it’s easy to find an A# for example because you know it’s right next to A!
Once you have that down,?memorize?a few spots on the A (3rd string), like C (3rd fret), D (5th fret), and E (7th fret). Then when someone says D# you know it’s just one fret up from D (6th fret).
Another handy thing to remember is that it’s easy to find an octave (the same note) from any note on the 5th or 6th strings. For example, if you are playing a G on the third fret of the 6th string you can find another G (one octave higher) very easily. Just play the note that is 2 strings down (on the D string) and two frets over (the 5th fret). You can hold both notes at the same time with your first and third fingers and you can do that from any note! So if you’re wondering what the 7th fret on the 4th string is, just go two frets down and two frets up. You’re now on the 6th string 5th fret, which you know to be A! They’re both A. Ok, I’ve already said too much.