Kytha's right, approach from the ground. Zelda's approach from the air only really has four/five options, being:
1)FAir (really predictable, and punishable)
2) NAir (hard to get close enough to hit with)
3) DAir (don't even try if they're on the ground; I wouldn't even try if they're in the air)
4) BAir (I guess you could try to jump behind them and use it, or if you think they'll roll behind you... but generally you'll get destroyed)
5) Airdodge (self explanitory; try to follow up with an USmash or a DSmash, maybe Naryu's Love if you need invincibilty frames)
*I'd include Farore's Wind, but that's not really a great idea either. Also, you can just FW off the ground too.
Basically, all of Zelda's air options are risky in some way with sweetspots and whatnot, so it's far safer to approach from the ground, where you have a pretty safe dash attack, a decent ranged FSmash, a decent grab, tilts, hypen-dashing, and other options. Approaching from the ground is better, period.