when playing my acoustic, I use my middle, ring, and pinky to form the A chord. Using the last 3 instead of the first 3 fingers opens up a bit of space. With my electric depending on the song (rock) lots of times its quicker and easier to just bar the 3 strings with the index finger. Pretty much a n00b myself (coming up on 1 year of "serious playing" w/ several years of "guitar ownership") this may or may not be the correct way but it works for me!