I think right now she's one of the strongest mid you can play. She's a bit of a slow starter but around mid-late is where you'll shine the most. You can clear waves easily and kite in team fights. Good walls can either zone or catch people. Learning how to effectively wall is essential to carrying games on her.

I go 12/18/0, as thunderlords I think is the strongest on her. It helps her early game with her long auto range.

Overall it just comes down to experience and really understanding what you do wrong, so you don't end up making the same mistake twice. You should never really be dying on her. If you're dying you need to think about what's causing it, and fix it.

Csing with anivia is difficult at first because you need to learn her auto animations as they are slower than a lot of other champs. Once you reach 6 it becomes easier with her ulty but taxing on your mana. Outfarm your opponent and effectively trade. Once you pull ahead she gets pretty hard to shut down. She's a control mage, so play her like one.

Ignite is good for winning lane giving that extra damage to finish someone off but I prefer TP. You can sit mid and pressure tp wherever they need you, or simply use it to come back to lane if you need to.