I'd say accessories is a good way to start!
As far as belting is concerned, I think you gotta go with what looks best on you. I think I've seen all of the variations you mentioned work on someone.
I'm 28 and still wear leggings. My mama is 57 and still wears leggings. I think at 30 you're safe, but I'm definitely in the LEGGINGS ARE NOT PANTS camp...so keep your goodies covered for sure ;-).
Here's some belting inspiration for ya: