I feel I might be looking at different images to those posted above...
#1 looks like it's been created on face in the hole (selective brightening work on the face???). The background is darkened far too much for me.
#2 I'm not really sure what to say to make this better... I'd probably leave it out of the set. The pose looks a bit awkward and I'm not a fan of the bunch of bananas (fingers all pointed down facing the viewer). It also seems the color is a little off (too warm for the scene) and the white has been taken out of the greys too much - did you use the selective color adjustment layer and adjust the neutral???
#3 is not bad.
#4 the darkening of the background and isolation of the model looks bit strange - would have to see the original to comment a bit more positively.
#5 Not a fan of the green and the amount of processing has left a serious degraduation in IQ for the shadows. Was this a .jpg that was darkened???
#6 Good idea but again, background is the let down for me.
#7 Very good.
Over all, I feel the area that's a let down mostly on this set is the subject separation, which appears to have been down in PP with making the background darker. I just think it looks a little too over done and easy to spot. If there's one thing I'd work on in the set, it would be working on the PP and going for a look that isn't so in-your-face obvious of what's been done.
Sorry I can't add much more to it that that - I'd have to have a play with a RAW to illustrate what I mean as it's difficult to convey in words.