A health contract is important. As far as you picking the pup up and looking it over...the ears should not have an odor to them and you don't want to see a rash on the belly. You also don't want to see a lump (hernia) on the belly. The pup should not wobble AT ALL when put down to walk. The gums should be a healthy pink color....not a white color. The pup should not limp. Eyes should be alert and shiney and not glazed over or tired looking. It is a little bonus if the pup will let you place it on its back in your arms or on your lap.....that is a trust issue. Well, I guess I could run on and on, but these are a few things you can look over for yourself.
Wishing you the very best and a healthy happy puppy!