I've been asked this question a lot over the last few years. When you are the worship leader in charge of a band, how do you actually lead - what is your role? So, here are a few thoughts that might be helpful...
Your first role is to lead worship through the way you live your life. There really is nothing more important than this!
Secondly, if you are leading worship in church, your role is to remember that you are part of something bigger. Nothing in church happens by accident, there is a whole vision being worked out - and as worship leaders, we play an integral part in that. Make sure you hook up with your pastor (or the person who is your point of contact) to talk about whether what you are doing is connecting with the vision and with the congregation. Ask questions about your song choice, the way you lead, the time frame you are using, and all of that sort of stuff, just to make sure that you are on track. We are servants first - sometimes with the whole music thing, we can be tempted to think it's about music and not ministry :)
Thirdly, we are there to lead our band. In the band, everyone has a level playing field - everyone can make suggestions on arrangements, everyone gets to bring their creativity - but, as the leader, your job is to take the lead - or in other words, to have the final say. It's a little like a captain in a football team - they are the boss on the pitch, whilst under the authority of the coach, the boss overseeing the game (or the pastor in our case).
That's it in a nutshell, but if you have some more questions on this, or you are facing a particular situation that you're not sure about please feel free to ask, and I'll write some more about it...