I started with tongs, feeding shrimp. My cuttlefish refused everything else. I then starved him for a day and he hunted a crab.
Soon after, I started replacing the tongs with my fingers. I never put much of my hand in, only the fingernails pinching the crab in place. The first time I tried it, the cuttle lunged at my hand to take the crab.
Now, he often sticks his tentacles onto me and doesn't let go...I dread the day that his beak nips my hand!
I also weaned him onto frozen by feeding live shrimp, then freshly dead shrimp that I stimulated movement with, and then I starved him a little to make him hungrier and he took a dead thawed one. Now he takes anything without complaint.