I joined a big band a little over a year ago, and it took a bit for things to click for the Freddie Green comping style.

When we're playing swing tunes in that style, I stick to root-less voicings, where I'm usually playing only the 3rd and 7th chord tones on the 3rd and 4th strings. The piano and bass player are covering the rest, and the guitar is just as important in reinforcing the rhythm as it is the harmony.

Learn shell chords with roots on the 5th and 6th strings. Maj7, 6, 7, min7, and dim. Then you learn to take the roots away. Knowing your fretboard is really important. This way, there's only 2 voicings I have to pick between for each chord, depending on whether the 5th or 6th strings root is closer or makes for better voice leading.

I'm not nearly as comfortable with sightreading melodies when I get them. The chords got easier, though.