Plan ahead. Come prepared. Make a syllabus, and if you know who's coming, tailor the workshop specifically to their needs. If you plan to ask the musicians to read sheet music, make plenty of copies before the workshop. If you'll be playing DVDs or CDs, arrange the audio-visual equipment ahead of time. If you'll have a band with you to do the workshop, hire the musicians, practice with the band ahead of time and make travel arrangements.
Understand some of the basic elements of group communication. Be able to communicate effectively with a group; know how to keep the attendees focused, and be ready to improvise if the class does not go exactly according to plan. Set up a format for questions and answers. Have enough relevant material to hold the attendees' attention for the duration of the workshop.
Take a deep breath and pray before the workshop. It's important to feel "grounded" before the class, to be in touch with your faith and to give thanks for the opportunity to minister music. Your attitude and presence will have a major impact on the atmosphere of the room as you begin the class.
Be prepared to address the basics of any band situation, especially how the musicians can listen better to one another. If the musicians are playing too many notes, help them understand the value of space and rests; if they're hungry for a more sophisticated sound, show them chords and approaches that can help take their musicianship to the next level. Discuss how each musician works together, how the singers work together, how the band and the singers work together and how the full band supports the minister. Put everything in the context of gospel, where the music is less about putting on a show and more about deeply connecting with God.
Answer questions and demonstrate examples of the concepts you've discussed in the workshop. Give the attendees feedback if you hear them play, and if you bring your own band, be sure to introduce them and thank them. Aim to close the workshop with a prayer, gratitude or a song. Be ready to give out your business cards and sell CDs at the conclusion of the workshop, and thank attendees for coming.