Mike, these are much better than my first forays into photographing people! I can tell that you have a good sense of light and composition. Having those skills in place already means you can work solely on the interpersonal aspects of photographing people.
If you believe that it's perfectly fine to photograph strangers without their permission, that will show in your confidence with your camera. 90% of street photography is in how you carry yourself. If you seem like the good-natured guy out with a camera, possibly a tourist even, randomly taking quick snaps, I doubt anyone will question you.
A smile never hurts, especially when directed at no one in particular. Hopefully you are doing this because you enjoy it!
People don't respond well when they feel like they're being watched, especially watched for an unusual amount of time by a stranger, so pointing a camera at them while you carefully focus and compose tends not to work.