A couple things:
1) I don't know that I care completely for the "abandoned worship" comment under tip #4. I don't mind a whole-hearted attitude in our church singing, and some spontaneous riffing is totally appropriate at times; but so often church folks use that term "abandoned worship" to refer to the "forget about everyone around you, personal worship experience." There are some theological problems with this. When we gather, we always keep in mind the people around us in the congregation, seeking to build them up and love them. We should never be so abandoned that we forget that they're there. Anyway - maybe this is just a semantics thing. Point #4 is great, though.
2) I really like the last point, on expressiveness. I'm a big fan, on our team anyway, of encouraging genuine expressiveness, not fake enthusiasm. You don't have to clap on stage, or close your eyes in a "holy pose" during singing; but it's important that everyone on the team is visibly engaged with the songs we're singing, and not looking bored or flippant while we're up there leading. As leaders, we should fight to be genuinely engaged with our songs and our congregation, whether it's an anthem of joyous praise, or a minor-key lament. That's part of the challenge in leading a church to sing - we have to fight to have soft hearts, engaged for real with our hymns and songs, because it's good for us and our gathered congregation takes its cues from the folks leading from the front.
All that to say, here are the tips for church vocalists!
- Blend
One of the keys to good Backing vocals is learning to blend so however many vocalists your have it sounds like one voice. So watch the lips of the worship leader or lead singer and try to match their starts, stops, phrasing, volume tone and vibrato. - If more than one BV stick to your harmony part
If you have multiple BV harmonies try not to cross over into another range. So if you are singing lines above the melody don’t go below it if another BV is taking that part. - Riffing
Vocal riffs are kinda like lead guitar runs. They feel great for the person doing them but can be so easily inappropriate if overdone or used in the wrong place. So choose your moments wisely, maybe use riffs on ‘out there’ moments to encourage abandoned worship. Even if your riffs are great too many of them can get irritating really fast. - Don’t upstage the lead vocal!
Again the BV’s role is to support the lead vocal. Most people in congregations aren’t that musical and actually get confused if they can’t follow a clear lead so be careful that your BVs don’t do anything to cut across that melody. - You don’t have to close your eyes and adopt the holy pose
One of the most worshipfully helpful backing vocalists I ever saw used to subtly use sign language as she sang to help her express the lyrics. It wasn’t supposed to be for anyone else’s benefit but her own and the gestures were very discrete but because it was genuine worship it was a very beautiful thing. Whatever gestures you make just be natural and mean it and sincerity will come across.