It is important that the worms, just like you, receive a varied diet. So give them something of everything. It also helps if you cut the food smaller. They can then process it more easily and quickly.
Vegetable and fruit scraps (not too many citrus fruits and no vegetables with oil/butter/herbs/salt on them)
Cardboard / egg cartons / newsprint (all without glossy paper)
Eggshells
Tea bags and coffee grounds
To leaf through