I'm not an expert but I am willing to share my opinion on your shots.
Of the images posted, I really like the compostion of #2 and #3. A bit of post processing work and they could really shine. I did a quick b&w conversion on #2 using channel mixer (red 42/green 55/ blue 6) and added a slight S-Curve to boost the contrast. #3 also could use a bit more contrast. I'm not sure what software you use but I'm willing to exchange a few PM's if you want some help.
Most of the non-fireworks images have a strong compositional element. This shows you have a good "eye" when composing your shot. In general, the images look snap shotish because the light is very flat. For those taken outdoors, it appears as if the shots were taken in the middle of the day with the sun directly overhead.
The most interesting fireworks shots I have seen have something else of interest in the image, a skyline, people, or a building. Here's the best I've managed so far.
Hope this helps.
Tim