Answer:
To sing them, or pass them on. Make sure others learn them and sing them to others
To become a regular (singer or audience) at a contemporary performance order to support others in the preservation of wonderful songs. Adapt them. Not too much different to the above, but updating songs to reflect more modern happenings can help to keep the tunes and the general message within the song alive.
Research the origin of the songs to seek their provenance and to add depth to why they were originally written. So many good songs have been lost with the passing of old singers. Let's not lose any more.
