Keys to saving our youth, which are apparently mostly mysteries:
1) Get them involved in the spiritually transforming works. Not just in their callings. Not in long church meetings with local leaders. Not in committees.
Get them involved in redeeming their dead.
Get them involved in missionary work
Get them involved in saving their living family members.
Those are the works that bring the spirit transformatively into a person's life. You cannot question that the gospel is true while your ancestors are conveying their sublime joy to you as you are baptized for them in the temple.
2) Keep them out of those things that are offensive to the Holy Ghost. This includes keeping them away from things that are not decent. It means not listening to music or watching movies or using sites that present immorality as acceptable, or that are sleazy in any way.
3) Keep them doing the basics that are required of all men: drinking from the fountainhead of the scriptures and communing with their father in prayer, and partaking of the sacrament as part of their weekly church meeting. Everyone knows that this one is needed. It is the other two that seem to be a great secret.
But if our youth become acquainted with the Holy Ghost by (1) doing the spiritually transforming works, and (2) not doing those things that offend him then our youth will learn to seek him out of their own accord.
I have greatly appreciated Elder Bednar's inspired push to get the youth doing work for their ancestors.