Well, here's my suggestions:
- Boost the exposure (you can do this two ways: if you shot at 100 or 200 put it up to 200 or 400 or afterwards increase exposure in Lightroom or other programs) because this will show the softness of their skin.
- I like the tint but I'd add a little red cause you don't want them to look too yellow. But it's nice to add warmth!
- I like the cropping I wouldn't do anything different!
- You could add contrast if you wanted to make their features jump out more.
- With portraits you always want to have a catch light in the eyes of your subject. It adds twinkle and makes the eyes jump out! Whether you meant to or not you got that light in every shot!
I hope these suggestions are helpful!