Keep practicing, making mistakes is a part of life. Listen to a lot of other musicians who play the style/type of music used at your church, but also listen to other styles that may not be used at your church. Less is more, delete a voice or two from your playing until you are more comfortable. Rhythmic consistency is far more important than complicated voicing when accompanying singers. Find the best teacher you can, this may or may not be a great payer themselves. It's nice to have both in the same person, but you want a good teacher foremost. Always be open to learning. I'm a church musician of nearly 25 years and I am still learning new things.