*Please do not attempt to touch someone’s dog without asking for permission first, and even if the person assures you that it’s fine, observe the dog’s body language and only proceed if the dog seems relaxed and willing.*
Many people, though well-intentioned, do not know how to properly greet or act around dogs. (This includes me too — until I started learning and educating myself about dog behavior, I acted the same way.)
People will often go straight towards the dog, bend over, and pat the dog on the head (while talking loudly and often making very high-pitched noises). However, the dog may feel uncomfortable, overwhelmed, or downright threatened by such a direct and sudden approach.
What you want to do is quietly walk in an arc (not straight at the dog—polite dogs do not rush at each other head on, but arc around each other as they sniff and greet one another). Do not make direct eye contact, stop and stand sideways, and keep your hands low to your sides. You can kneel or crouch down with a straight back, and be respectful of the dog’s space. Wait for the dog to come to you if the dog wants to.
If the dog does approach you, do not stick your hand out in the dog’s face. It can startle/intimidate the dog, and the dog really doesn’t need you to do that in order “to smell you.” Dogs have a great sense of smell that is far superior to our own. As mentioned above, just keep your hands low. You can avoid direct eye contact (which can be threatening) by looking away sometimes and/or blinking.
If the dog seems to be comfortable with you and wants to be touched, pet the dog on the chest or base of the neck. Reaching over their head can be threatening (since your hand is suddenly coming right at their face and then they can no longer see where your hand is going), and dogs generally don’t really like being patted on the head.
I am also including a few videos that are helpful for teaching children appropriate ways to interact with dogs, courtesy of Stopthe77.com. I like how they mention no hugging, no kissing, and no putting your face close to a dog’s. The “How to Kiss a Dog” video gives kids a great substitute for how to channel their energy into appropriately expressing affection (kiss your hand and then gently wipe your hand on the dog’s body, avoiding the face.)
(To see them full-sized, just click on the image.)