Praising your dog at the wrong time will teach him the wrong things. We have to keep it simple with dogs. Whenever you praise him, be it with a treat or a friendly word or pat on the head, you are telling him that whatever he did immediately before the praise, is what he did right.
For example if your dog is scared of a flying plastic bag and you talk to him with a soothing voice while patting him on the head, you are telling him that it is ok to be scared of that plastic bag. Instead you should walk him sternly towards the bag until he understood that there is no danger at all.
Here are some behaviors that truly deserve a praise. Give praise when your dog has been:
Do NOT praise your dog if he is:
Show your love by understanding your dog and giving him what he needs: love at the right time, rules, exercise, and walks walks walks.