For composition, you can take 2 'L' shaped pieces of non-transparent paper or cardboard, and place them at opposite diagonals, and then move them both up & down and left & right over your screen or print, thereby masking different amounts & areas of the photo, to see the effect of different compositions.
For instance in your 2nd photo (the one of the bride gazing off to the side) you could crop the entire left 3rd of the picture, that way the subject wouldn't be dead center, and with the left side of the picture cropped, the open space she is gazing into on the right side of the picture would gain more impact, creating a more wistful or dreamy look. BTW, I love the rich colors in this photo.
I like the shot through the foliage of the 1st photo, but again you could crop the right 1/4th and the bottom 1/6th to eliminate uninteresting detail & draw the eye more to the couple in the center.
The tight crop on the 3rd pic is fine, and the pic overall is nice, if not terribly exciting. It's a serene look, but I'd rather see her eyes or some emotion on her face.
I'm not a big fan of the 4th pic. I understand that maybe you/they were going for something fun, but by doing so they've completely covered their faces, thereby missing out on potentially the most interesting element of the shot (the expression/emotion on their faces).
Also, while I do think both sets of photos look great, they seem to indicate 2 slightly different styles to me. The 1st set are more classical, tender & serene; while the 2nd set seem more carefree & playful (except the shoe shot, of course). While some classical/wistful shots are great, you could also research some tips or strategies for bringing out some of the emotional or playful sides of your subject's personalities. Not always easy to do, for sure, but something worth considering.