STEP 1 – Gather Worship Tools.
A carpenter needs a hammer and saw. A mechanic needs wrenches and screwdrivers. A nurse needs a thermometer and blood pressure cuff. A worship leaders needs music and wordsheets. Choosing songs that your group is already familiar with help you succeed. Consider songs that your church is currently using. I emphasize currently because in my more than 20 years of leading worship, I have played more than 500 different songs. If I used songs that I played only 5 or more years ago, most people would have a hard time remembering how the song goes. Most churches have about 30 songs in their current repertoire. Ask for a list and choose at least 75% of your churches songs to create your own 30 song repertoire.
Once you get the list of your churches current repertoire, you need to get your hands on the music. I think you would be best served by buying the CDs that have the music you are looking for because you have more options for searching for and arranging the music. Nevertheless, audio tape suffice but require a little more work. Unless you are comfortable with your singing voice, buy the recordings with the singers (some worship music publishers do provide music without singers). You can ask the churches Worship Director what CDs or tapes to buy. Other resources are WOW! Worship, WorshipTogether.com Music, Integrity's Hosanna, Vineyard Music and Maranatha Music to name a few worship music publishers. Another possible resource is the sound engineers. Ask them for a tape or CD of your church's Sunday worship.