Leading the people of God from the front in the worship of God is a very important responsibility. One of the aspects of this role is to introduce the singing of hymns. So often it seems to be done in a way that presents the singing of the hymn as merely a time filler in the service. A phrase of the ilk “and now we will sing hymn no …” is uttered; the congregation then get up and sing, but with no idea about why they are singing this hymn. So what is to be done.
There needs to be appropriate thought given to the choosing of the hymns in the first place. Are the hymns appropriate for the occasion? Do they have an order which leads people along a pathway so as to have an appreciation of worshipping the Lord together? Do they fit in with the message to be preached?
With this established there then needs to be some meaningful leading of the people into the singing of the hymn. Mention what the hymn is about and/or why we are singing it. By your manner and phrasing convey that its is important that we are singing this hymn/song.
Also the one leading the service has a responsibility to make sure that the congregation know exactly what to do. Statements should be made explaining whether (and when) to stand or sit and direction given about any intricacies in singing a hymn such as a refrain.
Remember, if you are leading from the front, you are there to serve the people. You are there to facilitate them really engaging with the worship of the Lord.