I got into the car yesterday; put the key in and started her up. A couple started my way and walked around the car; I thought to myself "remember when?" What I was remembering was when a direct approach to my car would send Luke into guard mode. It was fine if someone walked by my car; even within inches was fine but just don't head straight towards it.
A direct approach for a dog is a dominant display; of course you must watch what the body in it's entirety is saying but in general it means dominance. Depending on who is being approached factors in as well. If a dog wants to send a neutral or non threatening message to someone or some other dog then they approach at an angle. When non house sibling dogs are out playing you will often see head turns, sideways advances to one another and huge circle approaches. Often young dogs will also lower their body posture while creating a sideways approach.
This is canine mannerly greeting communications and not all dogs are cued into delivery or reading. I remember one day way back when Luke was but a young'n and over flowed with enthusiasm. His zest for greetings got him into trouble quite a few times. One time in particular he saw a white German Shepherd across the field; nothing I could say was going to stop him from going to greet her. Once he left I stopped calling him and let her do the work; I watched as it unfolded. It was obvious that she was a very mature and confident female; she stood unimpressed as he ran straight at her, a foolish mistake. He ran bubbling over with joy until about 20 feet away when he finally noticed her body posture. He tried his best to jam on the brakes seeing that she was none too impressed with his charging approach, he completely altered his communication. It quickly changed to a modified circle, head and tail lowered as she then charged him. He turned on a dime and high tailed it back to Mom, lesson learned.
Body posture, angle, eye position and intensity all factor in with canine communications. When I meet new dogs I always assume my default position; a non threatening neutral one. Sideways is a common position for me to be in and it comes as naturally to me as walking. Unfortunately photographing dogs can be difficult but I do it; often my camera staring at a dog is very intimidating so I will turn sideways and shoot.
When you meet a strange dog, a dog that is not yours or even your own insecure dog, turn sideways. Making a direct approach can be interpreted as rude all the way up to scary. Are you directionally challenged?