Are you 'shooting from the hip' when taking these? i.e, are you on the move? Looking closer on Flickr there seems a touch of camera shake in the colour image [check the brick work and the man, there's a tiny bit of motion like you moved while firing. You could up the ISO a stop to 800 and this would allow you to double the shutter speed. Or, you could have shot at F/4, which allows for the same. It's just a matter of balance, you'll get a feel for what settings suit the situation, after some time you can look at a scene and dial in the settings before taking a shot. I love driving people nuts by saying things like 'That's ISO 3200 weather right there"

You're doing fine though, being new to manual settings, took me a while to really get the exposure triangle into my head. But it does become second nature. On the move, shooting street though, I would prefer going with a semi auto mode , I like Aperture priority, set that and the camera will take care of shutter speed and ISO -some prefer shutter priority where 'freezing' the moment without any motion blur is important. I don't mind any of these modes, there's little between them only full manual is better suited to when you can take your time each shot.