Have you got every spell outside the carnivale? There are higher level spells that make older carnivale stages much easier aswell as things like aetherial mimicry, oGCD primals spells and the final sting combo.

Other than that, there’s no catch all advice, you have to take each stage one at a time because they all have their own strategies, usually involving some kind of gimmick. If there’s any stages in particular you’re struggling with you might be better off asking for specific advice for those stages.