i was self-teaching before i started working with someone recently. really more a friend who has a band, helping me out. anyhooo.....when i showed him what i knew so far, his first advice was "quit focusing so much on the rhythm of the song and playing only downstrokes till you get fluent in and comfortable in the chord changes, THEN bring in the strumming patterns. This helped me millions because I was trying to focus on keeping the rhythm pattern whilst ineffectively changing chords, and it sounded like crap...now, even just playing downstrokes, the chords ring much better, and more fluent between changes. when i feel totally comfortable with that, i will progress towards the rhythm of it.
that is my advice, as a newbie..... :D