Man shall live by every word of God. So said Jesus, repeating what the Law said.
Our lives are to be regulated by the Scriptures, the revealed will of God. The Scriptures however do not directly and explicitly address every possible cintingency of life for all times, people, and places. Therefore we must learn to apply the Word to new and varied situations. The question to be settled is "How do we obey the Word in this particular situation?".
God places elders among His people, tasked with judging. That is, applying the Word to situations as they arise. The ekklesia is by definition a jury of sorts. But this does not give any particular elder or group of elders authority to simply make rules as they see fit. The church's job is not to make stuff up, but to apply the Word by the leading of the Spirit. And the New Testament shows that the primary way the Spirit leads the church is through consensus among those praying and flowing in the Spirit (
1 Cor 12-14,
Acts 15, etc).
In addition, the church is commanded to do certain things, but not commanded in all the details of how to do it. It follows then the assembly must decide how to carry out those functions. Such decisions are local. All in the assembly should be in agreement for the sake of expediency. If someone thinks they have a better idea, the church should discuss it. Church is not supposed to be a dictatorship but a society, a community, a family.
But each member if they aren't backslidden will seek the good of the congregation and not their own pet wants.
Any rules an assembly decides upon ought to comport with Scripture. A good way to do this is to affirm what the Bible affirms, and avoid what the Bible avoids. If Scripture is silent on something, we ought not to presume to speak as if WE were the oracles of God. The Word warns against both subtracting and adding to the Word. We cannot make things sin that God hasn't, nor can we make things holy that God hasn't.
We need to pay close attention to our Lord's interactions with and opinion of the scribes, lawyers, and Pharisees. They sought to carry out their duty of applying the Law, but went terribly astray and were evicted from the kingdom. Obviously, it behooves us to identify and avoid their errors.