Remember those licks that you love from your favorite guitar player and cannot get immediately. Do this...every day sing the chromatic scale starting from any key.Do it slowly and as you sing,picture the interval in your mind as you go along.#4,5th,#5,6th etc.Licks you cannot get are usually difficult because the intervals are displaced by octave,rhythmic groupings are complex etc. If you can say from a starting point e.g. F# know how the b7th sounds in all all octaves (by practicing this singing and playing exercise). 'Unknown' and 'exotic' sounds will be under your fingers. These are a few of the things unschooled players like me devise to teach ourselves. It makes 'copying' your favorite lick dead easy.