[FidoTheYorkie]

Never hold a dog when another dog comes to say hello.
If you see the dog isn't friendly, just turn and walk the other way (if it is in a leash), try to never hold him unless it's really really neccisary, cause if you hold him up while he's in your hands he thinks you are saving him from the other dog, and that the other dog is bad.

It is very good for him to be in stress, it is very important at this age, if you don't teach him how to behave in those places then he will be scared there later and afraid of the noise.

Just because he's small, don't treat him like he's so fragile, a dog is a dog ! and it's supposed to be raised as one.
Let him walk by himself (In a 1-2 meter leash , not a flexi leash) , except if you sence danger (loose dog for example), just walk the other way and if the dog would come running up to you barking and growling then you can take him up, but try not to, it makes him scared and makes him really bossy if you always hold him.