Every three weeks, I stand in front of a group of people and play my guitar just badly enough to make them want to sing loudly and drown it out. It's called leading worship, and I'm glad that I have a team of instrumentalists and singers with whom to share the blame for anything and everything that goes wrong. (Notice that I did not say if anything goes wrong.)
The first obstacle to overcome is choosing which songs to include in the worship service. Between centuries-old hymns, decades-old folk tunes, and what's-happenin'-now entertainment-as-praise pop songs, there's a huge number of choices...and you're bound to get it wrong.
Not wrong as in "that song didn't really fit the thematic thrust of the service," but wrong as in "that song was too <fill in the blank from the following list: boring, fast, slow, old, unfamiliar, loud, soft, charismatic, fundamentalist, new-age, Calvinist, Armenian, post-trib, pre-trib, amillenial, fattening>." You see, there are a lot of opinions out there in the pews, and as with any classic compromise, you will always have those who are dissatisfied. As a matter of fact, as compromise involves nobody getting exactly what they want, everybody will be miffed at something or other.
Ahhh...ministry for the Master...