some dogs work well for praise or a tone. try different toys as reward.
using real life rewards works great (maybe nto so much in the training a new command but for reinforcing one) - ex: ask for behaviour before they can go eat, or go outside, or get pets, or go play wtih a friend. whatever follows the command is the reward.
ETA: for more food tips - cat food (wet), tripe, and warmed up human meats can be higher valu. warm weiners (zap it real quick in microwave) or ham can be stinky and rewarding.