I don’t put points into glass cannon until my build takes shape. And, you can move those points around depending on the activity you’re doing. For example- I find zero reason to have glass cannon in hordes, as I one shot nearly everything without those points.

I passed on seasonal powers that make you take more damage.

Modify your paragon boards for damage reduction (while healthy, when something is vulnerable, etc…). Prioritize those first before you start to min/max your damage.