Maybe use a circular polarizer, especially when the sky is in the background.
Also apply dehazing in post. It works wonders.
I hope you don't mind but I did a few versions with one click presets to show post options.
Also while doing so I noticed that there is a slight blur and a good bit of pixilation when zooming in even just a little. Could be the amount of cropping. Others could help with that.
Well, as long as people are posting - here is my contribution to an improved photo; I will leave the cropping to others.
#1, barbed wire not great.
Bridge shot nice but too centered.
#3 and #4 a little more interesting
Agree with all the other composition comments. I would add using a gold reflector or fill flash with gel to better separate the subjects and put some catch in their eyes.
If you want to reply, then
register here. Registration is free and your account is created instantly, so you can post right away.