I play songs. I used to play random chords but I like songs better. You can minister to people that way, but the right placement in the service is necessary, You dont want to take away from who is speaking. I do like Josh and play bits and pieces of songs mixed in with random chords or musical themes. This is also a time I may work on throwing in scales with my playing or some practice pattern.
I also listen to what is being said. If the speaker mentions a song I sometimes start to play it.