I’m a solid Gen Yer, as is my husband. And both of us teach Millenials at a university, and hang out with lots of them at our university parish.
Here are my suggestions:
Facebook, MySpace, and Twitter. Especially Twitter (this is too young even for me!). Get a cell phone, and txt wo spllng stff. It’s easy - just be lazy and drop all your vowels.
Don’t water down the faith! So many people make that mistake. Tell them about it straight; reach back into tradition. Kids really want Adoration, meditative prayer like the Rosary and the Divine Mercy chaplet, a way to offer up their suffering. But they DON’T KNOW HOW. You have to teach this stuff from the basics, and start small. For example, try 5-10 minutes of Adoration at a time, with specifics of what to do (read the Bible, pray this prayer, etc.). Start with the Divine Mercy chaplet rather than the Rosary; they have short attention spans, and starting meditative prayer demands a longer one. They need to get used to the act of it before they can sustain it (this is from personal experience).
Blog. Blog about all kinds of stuff, from popular culture to religion. Relate it all to God.
Get to know the world they live in.Listen to their music. Watch some of their TV, even though it’s pretty bad (in the US, we have the-N channel, which airs Degrassi). You need to do this so you can realize the terrible pressures, the lack of respect for life, and the insane materialism they live with.
Encourage them to move away from that materialism. Be an example of it. They know that stuff isn’t the end of existence, but they’ve never seen anyone who lives that ideal.
Most of all, you need to live for Christ. You need to be that example of someone who gives up all for Him, who strives to live in holiness. Christ can speak for Himself

.
Preach about obedience. They need to learn obedience to the Church and how to submit their wills to God’s. No one talks about this, and our world is in sore need of it.
Give them the saints!
And wear your clerics. There’s a certain authority that comes from it.
I’ll keep you in my prayers.