Watch the The A Team online guitar lesson by Brad Carlton from Chord Studies: Beginner Chords Vol. 2
In this A major progression you'll be using only two shapes with your fretting hand. Work on proper thumb placement in order to make your chord changes more fluid. It's ok to get some string squeaking at first, but over time you'll be able to clean that up. Rhythmically we're actually doing dotted half notes, giving ourselves time to move into position for the next chord.