How I am supposed to play Cassiopeia ?

How I am supposed to play Cassiopeia if she can't compete with AP Burst champions out there, her DPS is so low, even after finishing a glass canon build. She can't even gank supports and her only utility right now is to reveal bush and stun/slow yet, she still being out performed by a lot of champions in many ways. I understand that her play style is different, that she is DPS mage rather than a burst mage but right now she is being outperformed by many champions and she won't shine in early, mid or late game because her damage is not enough to 1v1 or team fight most champions. I tried to change my play style, to stay more alive so I could deliver more damage but it is ridiculous, I can't deliver enough damage, I can't even risk myself because it is just not worth to do. So, do anyone know any better way to play her ? Any working build or role that she can fit in ? I like to play Cassiopeia but playing Cassiopeia as dps mage is just not a good idea right now.