Dog aggression tips (new dog introduction)

Walking together is a great tip - thanks! His tail never really goes straight. He seems to be doing a little better about not growling as much.. When they are separated and any of the other dogs make noise (bark, play, etc) he runs over to the gate/door and starts growling.
 
Last night I was holding rascal on my lap while my fiancé held onto buddy's harness. Buddy ran over excited to give me kisses, but snarled loudly and tried to bit at rascals face. (He couldn't actually reach rascal)

One step forward, step steps back.. I think we will get there eventually
 
When I walk them together, how do I prevent buddy from biting rascal? Should we just walk them far enough apart that they can't reach each other? I don't want rascal getting hurt.