Watch the Two Five online guitar lesson by TrueFire from Beginner Guitar Explorations
Lesson Source: Brad Carlton's Chord Studies: Open String Chords Vol. 1
Open voicings for Am7, Dadd4add9 and Dadd4 can be used over pretty much any ii - V progression in the key of G. Your first and second fingers will serve as guide fingers. Be careful not to accidentally mute any of the indicate open strings!