Complete beginner here. I've only had a guitar for under 3 weeks. One thing I found helpful for chord changes was to watch the free online Justin Guitar tutorial. I really like this site, but I don't see the problem using all information that is out there. I found the "1-minute chord change" lessons very helpful. There is also an app that randomly selects two chords that you must switch between and then it times you. You can input the chords that you are studying and it randomly selcts amongst them. I'm still horrible, but I found this helpful and I am getting faster. Just keep concentrate on getting good tone.