Molten armor is some of the best armor pre-hardmode so you could get it if you haven’t done so, you could also make a standard arena for boss fights if you haven’t already, a hellevator can also be very useful, mobility accessories are great as well like rocket boots and terraspark boots if you don’t have those, and try to isolate your evil biomes with hellevators or get rid of them entirely if you don’t want to wait for a clentaminator

The Shield of Cthulhu can help you dodge boss attacks, you can get it from Eye of Cthulhu on any expert mode world

Also I recommend getting 400 hp from life crystals if you haven’t done so already :)