Start with “no” and “good boy” or “good girl” or “good (name of dog)” and be sure to inflect your voice to stern and happy for the right understanding. Once the dog understands this, he will want to hear the happy voice more. You might help it along at first by giving a small treat along with the “good” – until the dog “gets” your approval without needing a treat.
After this, you can try more words in your commands, or even whole sentences. My dog knows many whole sentences now – like “wipe your feet” “go get ‘em” “keep going” “no bunny no squirrel” “go slow” “go to bed” and such.
I am lucky that my dog picks up things after showing him once – like when retching one night, I saw a towel and put his face in it. After that he looks for a towel to puke into, so I keep a towel on the floor for hm to find. He’s a “polite puker.” He picks up things fast, and I praise him to let him know he did well, and I am pleased. He does not like the disapproval – the tone of voice (I do not smack him at all).
All my dogs have done well with positive reinforcement training. Some dogs are tougher, and might need more assertive training. PR