Here is a word from John Newton on how to pray in public. Newton, the author of the hymn “Amazing Grace” Dealt with many practical issues. The article, which was apparently a sermon, is about 4 pages long, but a worthwhile read. For a more humorous take read a modern version How NOT to pray
Here is a great quote from the sermon:
“The chief fault of some good prayers is, that they are too long; not that I think we should pray by the clock, and limit ourselves precisely to a certain number of minutes; but it is better of the two, that the hearers should wish the prayer had been longer, than spend half the time in wishing it was over.”