Agree with 412; all of these needed some form of supplemental lighting, whether it was a SOS*, reflector, or full-on studio-light. Also, watch your backgrounds and DoF. The backgrounds are too focused, busy and distracting to really be idea. Consider using longer, faster glass for shots like these. In the last one, you have some great leading lines in the form of the bridge railings, unfortunately, they lead the eye right past the subject and out the back of the image. These are definitely a good start, and I would suggest grabbing your friend for another session soon.
*Speedlight on a Stick