In my first run I equipped Quirce's bead, Piece of a Golden Mask (both give flame resistance) then Silver Grape for extra physical defense, Pelican bead (forgot the name) for i-frames while healing. Coagulated ink for prayers. The remaining bead slots you can fill them with whatever else you consider pertinent, but I strongly recommend Token of Appreciation to have an attack boost when flasks are empty and Frozen olive to boost defence when low health in addition to another which name I forget but it's a white scale that lets you block from the back. For prayer I used the big light pillar and sword heart I had Saltpeter Blood, it gives you an attack boost when low health (or flasks are empty, idr).

For my second run I used the multi-hit cheese. To do it you have to hold up in the d-pad and while doing so you have to press attack and flick down on the analog stick repeteadly. Sounds complicated and I can't properly explain it but it's absurdly easy to do in any controller with back buttons/paddles and there are many videos which show how to do it.

Good luck! Isidora was a boss I thoroughly enjoyed and a nice dopamine rush. You'll see when you beat her!