I am in agreement with Gavin save for the last part. The more I hear a cantor sing the more I don't want to sing, but not because of the "pretty voice" but because it often ain't so.

1.Start teaching them chants for the liturgy, psalmody, hymnody, et al., in school from kindergarten through 12th grade. Compulsory if need be.

2. If their parents sing enthusiastically in church, they will think it is a Good Thing.

3. Have enthusiastically supported choirs for all grade levels.

4. Get rid of the song leader who THINKS he or she is a cantor (these are not the same thing, and the former is utterly foreign to historical Catholic liturgy).

5. Get real organs and real organists. It is the organ (and no one else!) which leads the congregational song when played by an organist who really knows what he or she is doing.

6. Give enthusiastic support and parish-wide appreciation and respect for the parish choir, who not only grace the liturgy with anthems, but more importantly, provide leadership and tonal example to the congregation. If you have a good liturgical choir, the people should be 'swept up' into the sound of it so that all become one voice.

7. Stress endlessly that sung liturgy is normal and that not singing the liturgy is taking something away from it.

8. When faced with 'I don't like...' and such, respond as if that were the unfortunate and negative condition that it is (AFTER trying to encourage and be a positive influence).

9. There are times when all of us have had to deal with what seemed unsolvable challenges, but the importance of always conveying a positive and wholesome attitude about music and singing as givens is paramount.

10. Be sure that everyone (especially children and youth) knows that Jesus sang.

Get some trained singers (starting, if need be, with a choir of one) and insist on your own restraint. Don't be afraid of quiet time at Mass! Quiet time isn't a bacterium needing to be killed, but a great blessing. (Remember that the rests help give meaning to the musical notes.)

Never, ever, use a microphone, if you can avoid it. Bosses (be they pastors, headmasters, heads of liturgy committees or whatever) may require some use of the un-natural object, but since God doesn't need a hearing aid, and since the Mass is theocentric by its very NATURE your goal should be to reduce or (preferably) eliminate ALL electricity based amplification.

Use the unaccompanied voice if possible -- to let the congregation hear itself sing, not because organs are bad. If you sing some psalm-tone "responsorial psalm", with simple antiphons, you give the congregation the chance to contribute, and to understand when it is "their turn" to sing.

Choose music which can be sung well by unaccompanied voices. To illustrate my point (but by no means to limit the available music to only the music I will discuss) take Benediction. Most parishes, in my experience, know some setting of Tantum Ergo, O Salutaris Hostia and Holy God, We Praise Thy Name. Most people know a tune for Stabat Mater, for the Stations of the Cross.

Perhaps you could introduce a few simple Alleluias, and a sung Amen for every prayer which Father sings (which is to say, not merely at the end of the Doxology at the end of the Canon). Encourage Father to sing the Sursum Corda.

You will find that some people are opposed to this sort of thing for the simple reason that they have a defective understanding of any act of public worship of God. Others may be opposed out of fear of the unknown. This can be overcome.

Take heart: remember that in improving the environment of Catholic worship, your work is pleasing to God.

While I see the idea you're presenting and agree with it, the success shown in that clip can't be duplicated in every scenario... obviously (nearly) everyone in that hockey arena was fully knowledgeable of the tune and words of that song. This is not always the case with every piece of music.

If I've said it once, I've said it a thousand times....
If people are convinced of purpose, they will, like the poets of antiquity, sing it for the ages.
Why else is Holy Thursday a "favorite" Mass for most music directors?

Originally, I was going to have a two-part answer; the second being a more generalized version of RN's and melo's explanation:

1) Put down the microphone.
2) Sing something worth singing.

Adam,

It's like you read my mind.

http://www.ccwatershed.org/blog/2013/mar/6/how-do-i-get-them-sing/