I lead a Lutheran contemporary service, so worship themes are guided by the standard lectionary. That's my actual reply, BUT (still floating on JOY from an unbelievably moving worship service yesterday) in years of ministry I find the key message of love (everyone), hope and service throughout the Gospel. Our service begins and ends with praise music--we add a new song at the end of the service each week and rotate it backwards through the set for each service over the following weeks, so every praise song for us is introduced as a sending message at the end of a service. We started in April with "everyone's favorites" but now I'm choosing songs which are, as Chris concisely states, theologically grounded and singable, and also offer a fresh perspective on the Great Good News, that makes it accessible to newcomers and fresh to the long-faithful (e.g., any song by "Casting Crowns"). But for me, by necessity, it starts with the demo track--if the tune & message there "catch" me, I buy it (thank you Praise Charts--makes it SO easy). If it catches my band, too, I know we have a "hit." Some repetition (but not just short phrases) seems to work well - e.g., "Because of Your Love" and "Stand In The Gap." Maybe we're unique -we decided to go our own path in this, but it's a huge success--new faces every week, absent faces returning, etc. PRAISE GOD! It would surprise me if there was a single or average "formula"--we must minister to the community we find ourselves in, yes?

I echo what Chris has already said. The other factor for me is building a set list around the theme for today if possible.