mine isn't over-exuberant except to a couple of big male doggies that she LOVES :)
I'm still learning to asses the other's dog's body language, so my rule is to hold her back (she's highly obedient, so I just say "stay" and she stays back) and I look for the owner of the other dog to be close, see if he/she is ok and then look at the dog if it growling or teeth curled or one of what I call dangerous breeds (note to all -- this is my own personal position -- and I'm sure I'm wrong for many dogs, but hey, I'm just looking out for my dog) and then wait for the tails to wag.
Gypsy goes whole hog flat out giddy trying to solicit play and affection from every living thing she meets.
She’s just built that way...:)
There are *tons* of good websites on dog body language and you’d be surprised at how many expressions are not what they might seem.
Here’s a couple to get you started
http://www.pawsacrossamerica.com/interpret.html
http://www.diamondsintheruff.com/diagrams.html
I had to learn all this from just watching dogs for decades but thanks to the miracle of the internet, it’s all laid out very nicely for everyone to learn.
[to me, the internet is one HUGE free library]
:)