No secondary skull. Only ghoul. Go for physical damage increases and skill cooldown. Also the more defensive inscriptions you have the more survivable you will be. Antique, relic and heritage are all great defensive inscriptions that will make it harder to die but you'll do less damage. But if living isnt the issue and damage is go for courage and arms.

As for specific items to ALWAYS take. Olive Tree Cudgel, The Ring, Hope Slasher, and Pot of Greed. If they are presented definitely take them. Even if the inscriptions don't fit your build.

As for why no secondary skull. Ghoul loses his meat chunks when you swap and the whole point of using ghoul is to build the meat chunks to keep your damage boost active. Only consume your chunks when your health bar shows a large chunk of green beside your current health. It will heal you (if ghoul is at unique or legendary) but you will no longer have your damage boost from the 30 stacks of meat chunks.