Basic 3 Twist Dog
Almost everybody start learning balloon modelling from this basic 3 twist dog because it only involve a vary basic skill - locking the bubbles. You can complete it by just 3 twists. The following video shows the tutorial that teach you how to make the basic dog.
You can also modify the legs of the dog to create different posture of the dog as shown in the picture below.
A lying dog
A sitting dog
Dog climbing a tree
Amazing Dog
This is another version of a balloon dog, it's a little bit more complicated than the basic dog.
Do some modification on the nose and ear, you may get this:
Here is another one which is similar.
Snoopy Head Dog
This is another version of dog which has Snoopy like head.
Advance 2 Balloons Dog
I learned this from a book. It involves two 260 balloons.
The video below shows you another advance 2 balloons dog.
Advance Multi-Balloons Dog
Here is a multi-balloon dog from www.balloonutopia.com. Give it a trial. You will find that it is not as complicated as you thought.