I can understand someone just beginning to play the guitar practicing for 20-30 minutes. My fingers hurt like hell until I started to build up callouses. That being said; If you want to make progress you really do have to practice a lot. I've been playing on and off for 40 years and I practice 4-5 hours a day. Granted, I am retired but when I was working it was more like 2-3 hours a day. I do the same thing Jeff does - I practice scales while watching tv or sitting on the porch. If you not into scales yet- try playing all the chords you know 10 times. The key is repetition. Playing the same thing over and over will build muscle memory and it will also train your hearing so you will recognize a chord when you hear it played. I also taught myself to play but I wouldn't encourage anyone to go that route unless they had to. If your goal is to teach guitar I would strongly suggest you get a good teacher to show you how to play and teach.