Strumming patterns and chord progressions

For strumming patterns, I drift back to a few familiar ones all the time too, but I've been successful by consciously practicing a different pattern than normal to a basic I-IV-V chord progression (whichever you like best).  Try a reggae pattern (up-rest-up-down-up), then a rock pattern (down-down-down-down), then anything you want to make up yourself.  Play slowly at first, then build up once you've got the pattern.

For chord progressions, right now I think I dream in D.  Everything I try to write seems to gravitate to D-A7-whatever I feel like next.  G is the obvious, so when I want to sound different, I go instead to C or maybe E.  You should keep trying more difficult (and different sounding) chords as well; it will add a great deal to your writing arsenal.  I, like most everyone else on Chordie, have had lots of trouble with barre chords.  I got around it at first by playing Fmaj7 (xx3210) instead of F (133211), and now I like trying to mix in other major 7ths (Dmaj7 - xx0222, for example).

Which came first, the chicken or the egg?  I tend to write lyrics and music at different times, but I'm not sure if either is "first" more often.  I'll write down some nifty-sounding chord progressions when I'm goofing off with the guitar, then later I'll look through a few sets of lyrics and see what might fit together.