You’re doing very well for starting out. Your composition is good! Good eye. Everything’s subjective so that part of it’s fine.
http://www.photosbyanjanette.com/wp-content/uploads/2013/02/karim1.jpg —- pants look overexposed/high contrast? I don’t know if that’s done on purpose.
and the train tracks….—a little over exposed on the right.
On your last set, I like 1 and 4, maybe with a little bit of editing.
Out of curiosity, are you on full manual with your camera? Using the light meter? Also are you using Lightroom or Aperture? Shooting in RAW?