I often play praise and worship music, many times for churches on sunday mornings or for church retreats.  This can sometimes be a big responsibility but I find that if I prepare myself well, things usually go pretty good.  The best way to prepare myself is to make sure that I am familiar with all of the guitar chords necessary to play the songs.  Most praise and worship songs I find to pretty easy, many of them use the same guitar chord progressions, so if you know the key of the song, you can play it without looking at the music.