Welome to TPF!
Opinions per req:
1. Just a little bit hot, and I think your key needs to move a bit more to one side or the other. I prefer a less tightly composed image, but that's a personal thing.
2. Not bad; a little more contrast in the lighting and a bit more DOF wouldn't go amis.
3. Blue is almost NEVER a good colour for skin!
4. Not fond of the very OOF hand and flower in the foreground.
I think you've got some good potential with these, but perhaps a little more tweaking in post?
Just my $00.02 worth - your mileage may vary.
~John