The biggest mistake churches make in their by-laws is giving too much control to the wrong group of people. Too many church planters begin their churches by adopting the same by-laws their sending church had. This can be a great blessing if you've got the right by-laws, but can also be deadly to the health of your church if they are the wrong by-laws. There's nothing in the Bible that says we should have congregational voting. Why churches do it escapes me.
If you're a church that reaches unchurched people, here's what they are expecting: for the leaders of the church to lead the church. That's why we need to lay the right foundation and structure our churches in such a way that allow leaders to lead and make decisions in a way that eliminate unnecessary red-tape.