I am BIG believer in wearing as much black as possible if you’ll be performing up front at a church. Conservative pieces are best, but you can still get creative with cuts/textures. (I used to do this every weekend for years too and oh my god, thought I’d never wear black pants again for as long as I lived.) Still—I think a mostly black outfit looks the most chic and appropriate. Since it sounds like you can go a little more casual, I included a few fun things. 

This is the most conservative and typical of what we wore for more formal concerts. A long black dress ($45) with a jacket ($35) and mid-height heels ($55) will be your bread and butter. It may be a bit more dressy than what you need, but it’s good to have on hand. 

This is more playful, but still appropriate. The top ($49.50) stands out, but it’s cut high and will look sleek with these pants.  Go for a higher shoe ($37.33) if you won’t be standing for too long. 

Not sure if you’re okay to wear prints, but if you are, keep it simple with a striped top ($12) tucked into a pencil skirt ($59.50). These Target shoes are cute ($30). If you have to be standing for a while, go for lower heels or pointed toe flats. 

This pretty close to what I used to wear every weekend. Ankle-length trousers with a high-waist are flattering ($45) when a fitted 3/4th-sleeve or long-sleeve tee/blouse ($17) is tucked into them. In the winter, switch it out for a turtleneck. Sling-back pumps with a mid-height heel ($42.43) are comfortable and look good with the cropped pants. 

Once again—if you can do prints, go for it with a polka dot blouse ($69.50) tucked into a maxi skirt ($30.55). Keep the shoes simple, like these practical (but still cute) pumps ($39). To go more casual or comfortable, you could choose black sandals or black flats. 

I hope this helps and gives you a few ideas! Have fun!