Good try. A few things to take note of.
1) Soft focus. The focus isn't accurately sharp on the subject's eyes.
2) Lighting and shadows are harsh and uneven. Try to use a diffuser.
3) Try to apply Rules of Thirds in your shots. Centralised shots are not attention seeking enough.
4) Some shots are noisy, example, #1 and #2, which are probably due to cropping or high ISO settings.