That is a very nice first run!
If you're looking for a couple ideas (and I'm being extremely picky here):
I don't do greens but I've heard that judges like those greens to look like a golf course.
Chicken and Pork boxes both have some smudges around the outside of the box. Get a cup of water and a small paint brush, dip the brush in the water and wipe out any smudges. Make that the very last thing you do before closing the box. I know some judges that are fanatical about the box edges being absolutely spotless.
Chicken. Work on your trimming to get the pieces as uniform in shape as possible. Compare the top right piece versus the lower left. Excellent gloss. Be careful not to put too much sauce on the chicken. It turns into a mess for the judges. Also, try adding very small flakes of oregano (or some other spice that won't affect flavor very much but is just big enough to see, not black pepper!) to your sauce. It will be visible in the sauce and adds a small bit of depth. It's just a visual trick. I see the front piece has a little bit in it.
Pork. I don't see very much wrong there. The box is laid out nicely. Possibly make the medallion slices a bit thinner? The judges might think you're trying to hide overcooked meat by slicing wider (that's just my guess). I've heard that judges are getting tired of the look of pulled pork, however I know this judge still likes it! You've got six slices in the box. Never put exactly enough of anything in the box (6). Always pack enough so that the last judge gets to choose between 2 or 3 pieces. I know it sounds crazy but getting stuck with the last piece can sour a judges opinion.
Brisket. The left side pieces look pretty darn good. Nicely uniform. The third one from the top has something on it. The right side ones should be just as uniform. The slices need to have that bottom fat layer removed. There are seven slices, I usually put 10 or 12 slices in the box (same idea as the pork slices above). The middle slice has some pretty heavy 'saw' marks on it. Work on making the entire slice in one pull witha razor sharp knife. Maybe add tiny little bit of a sauce to the slices if for no other reason than to add some color and a gloss. I've had good luck with dipping each slice in a very thin sauce and letting the majority drain off before putting it in the box.
Again, I'm being VERY picky here and I think you guys did a very respectable job. My comments above are completely intended to help, not bash.
Russ