Watch the Minor Triads online guitar lesson by John Stowell from Modern Jazz Improv
Given the number of major and minor triads that are usable over a major chord, focusing on triad pairs can be a way to assimilate and internalize the harmony. Pay attention to the intervals of the various triads as they relate back to a tonic center (C major, for example). Over time, you will be able to visualize and quickly find any b5, #5, 6,9, #9 etc., relative to a major chord. The various triad shapes/patterns become overlaid templates on the neck for you to utilize and create your melodies from.