Learn basic music theory. Whether you want to be a songwriter or you just want to figure out that really cool lick by a musician you like, the basic is in music theory will help A LOT. I'll start with the concept of "intervals". An interval is the difference in two pitches, usually described in 'steps". In Western music (as opposed to Far East music), intervals are counted in multiples of half steps, with 2 half steps making one whole step. (because: math) On a guitar, each fret is one half step. If your think of the open string as a starting point, fretting a string at the first fret will raise its pitch one half step. the interval between the open note and the fretted note would be one half step too. Fretting a string on the second fret raises its pitch two half steps, the same as one whole step. /the interval between the open string pitch and the second fret pitch is therefore one whole step, though people rarely use the word 'whole', they will just say ' one step'. Note that the interval between the first fret pitch and the second fret pitch is one half step. If you fretted a string at the fifth fret, the interval between the open pitch and the fifth fret pitch would be two and one half (2 1/2) steps. Intervals are important in the construction of scales, chord, melodies, harmonies and just about everything else in playing and composing.