In the church I am attending, men are required to put on a necktie when they are on duty as ushers, worship leader, and so on. I believe this is the practice for most congregations. They would mostly put on neckties of a dark color, setting a solemn and serious tone for the worship. I am fine with that. However I think that if they switch to neckties of a lighter color, that can turn worship to a lighter mood. After all, worship is supposed to be a joyful event.
Worship the LORD with gladness; come before him with joyful songs [Psalm 100:2]