The band I am in got started by playing as a worship team and leading when our church hosted outdoor services. From there we slowly got invited to other outdoor services, then combined services, and then on to bigger churches that wanted to expand into modern worship. We now play at about a dozen or so events every summer and the odd event through the rest of the year. Not overwhelming, but we love every opportunity. We've also had the opportunity to play at several events that had nothing to do with religion or Christianity, so it was a great opportunity to witness through our music to a completely different crowd. The best was when we were asked to be the solo group on July 1st for the Canada Day celebrations in the park.
Anyway, my point is to start small and over time it might build to more. Let your church know you play guitar and make yourself available whenever they need you. Just stay faithful with your message because you never know who's listening and who needs to hear the words.