Dear,
It’s very nice to meet somebody who plays worship music on the harmonica. I’ve been playing in church for more than 20 years. Firstly on accordion, then harmonica and other instruments. Now I’m playing mainly on piano. If I can advise You something: try to play by ear. Listen to popular songs and play along. Then buy a harp set with the most popular worship keys: D,C,G,A,E,Bb (ordered by usefulness in worship) and join the worship group in Your town. I think that You will be welcome in a baptist or charismatic church with Your harps.
Playing worship is a great spiritual and musical adventure for me. We still need to listen to other musicians, church and the spirit of Jesus, of course!
Harmonica is not the main instrument in a worship band, and we must play not too much, but good notes in a good moment can be inviting to open the heart for the Lord.
A couple of years ago, in our church, some boy asked me to learn harmonica. I made a little songbook for him. This book contains only Polish-language songs, but some of them are translations from original American songs:
Open the Eyes of My Heart, As the deer, Only by grace Can We enter.
All of these tabs are prepared to play first-position without any bends.
So pick harmonica with key of key of song and just play with band. Good moments for harmonica are intros and outros.
Here are tabs:
Hope this helps You 