I have used a spray bottle...but i mainly just use my voice...he knows when i mean business...when he is doing something he shouldn't be or his attention is , say on another dog.. I make a load deep gutteral 'ahhhhhh' and tell him to 'come' or 'leave it' depending on the situation..and he knows to continue on that path means trouble

I can't say enough about obedience schooling, basic commands are a must, specially as i have a large not overly friendly to strangers dog that without it would be a menace to people and difficult to live with, i personally never have or will use food treats for training...

I am boss and he knows it.