Watch the JAM: Triads and Seventh Chords 1 online guitar lesson by Susan Mazer from Hands On Guitar: Beyond Beginner
Have the chart in front of you before you play along. Practice each chord slowly and be sure that you know where your left hand is supposed to go. Your hand only follows what your head tells it to do. Remember to keep common chord tones down. As a review, you can also try writing out each chord from memory using a blank chord diagram.