[help] Where am I supposed to pet a dog that I've never met before?

I asked the owner of a dog at the park if I could pet the dog and the owner said I couuld. I was with my friend and when I pet the dog, I pet it between the ears, right or above the eyes. My friend said I wasn't supposed to do that because it could anger the dog. He also said that I was petting him wrong with my hand or something and I was supposed to keep it tucked in case he bit me to reduce injury. So, how do you pet a dog correctly and where do you pet it for the first time? My friend could be messing with me though, but I doubt it. via /r/dogs http://ift.tt/2srkLYT