What do I raise with in this game? (PLO HI)

[MasterShakes]

I've played PL/NL Hold 'em, limit O8, and limit HE, but the few times I've played PLO HI, I've had no idea what I should be raising with preflop. What hands should I be willing to get all-in with? What hands are a favorite over just about anything? In other words, what hands are similar to AA and KK in hold 'em, if any? I get the idea that this game is more about the draw, and I could envision never raising preflop, but then again, I'm pretty inexperienced with this game. Enlighten me...