You could always start with retrieving certain items (i.e., newspaper, keys, slippers, etc.). How about dancing on his hind legs, the treat on the nose trick.
Teach him helpful stuff too. My old guy used to love to carry grocery sacs in from the car. Open doors, turn on lights, fetch cans from the fridge, carry laundry to washer, fetch the phone, carry small gardening tools, endless things they can help with. The more they learn the more easily you can add tasks....