Watch the G Chord Pattern online guitar lesson by Stephen Mougin from Bluegrass Rhythm Evolution
In a G chord, pluck the low E string, strum, pluck the D string, strum.
The trick with this one is skipping your pick between the low E string and the D string. To break it down, grab a metronome and practice just picking those two notes back and forth. Once you've got a handle on it, try adding the strums between them.