Learn how to transition to different chords. One way to become proficient quickly is to learn how to transition between the various chords quickly. These transition periods are often the hardest for beginners to play when they are starting off. The more you practice between switching to different chords, however, the better you'll get at doing it in songs. Practice switching between open chords like G, A, E, and C. 
Manage the finger pain. There'll be a point at which things will seem bleak: you can't quite get to each chord as fast as you want, your fingers are killing you, and it seems easier to put the thing back in its case. The reason most guitar players stop playing a few weeks in is that it hurts. After a couple of months and years of playing, callouses will build up on the fingers of your fretting hand that will greatly reduce the pain of pushing down the strings for long periods of time. Everyone who learns to play the guitar has to deal with sore fingers at the beginning. Learn to love the pain and associate it with everything that you love about music and the guitar.
Intermediate Guitar Class - Open to all ages, from age three to one-hundred sixty-three, but an audition or permission from the instructor is required. This class is intended to be challenging. Topics covered may include movable bar chords, song forms, repertoire development, fretboard mapping, improvisation, and other advanced techniques. New classes start every month and may be repeated as often as you like. Cost is $85 per month (4 hours).