From a pastor-friend:

A couple of years ago I prepared training manuals for those involved in worship leading and preaching in our church. They included a section on Dress and Presentation where I said:

“Dress

There are no hard and fast dress standards. Your dress will depend to some extent on the congregation and the occasion. It is probably wise to dress at least above the middle range of your congregation – you need to be careful not to be too “dressed up” or “dressed down”. Dress should be neat and reverent, not drawing attention to yourself. Your desire is to draw attention to God. Take care of the little things; shirt tucked in, tie straight, hair in place (if you have any), shoes clean (yes! even shoes get noticed), buttons correct etc.’

Manner

As with dress, manner is important. People are just as sensitive to the para-message of body language, (posture, gesture). The leader must be in control, displaying joy at the opportunity to worship, while being relaxed, warm and earnest. As leaders you must discipline yourselves to avoid behaviour that might distract or irritate. Your general manner needs to reflect the reverence of the presence of God, there is a sense in which you are the Moses or Aaron standing between God and people.”

There is a wonderful article in the form of a letter regarding suggestions for worship leaders on http://www.laudemont.org/a-sfwl.htm which I included as an appendix win the booklet for worship leaders.