I encourage all dog lovers to read a lot of good books about dogs training. Training dogs turn out not to be intuitively obvious, and the more you learn, the easier and more fun it will be.
When I first meet a dog, my primary attention is on the dog's center of gravity and his breathing. Is the dog leaning toward me, or standing square over all four paws ? Is the dog frozen still, breathing normally, or breathing too fast with shallow breaths ? At the same time, I'm looking at the dog's mouth and eyes, where there is a lot of information, but being careful not to stare directly at him. Tails are also important, but not as important as what's on his face, and you simply can't take everything at once.
Honing your observational skills is directly related to having a better-behaved dog, because what you do around your dog should be related to what your dog is doing.