Sinewsworn Loc: Port Orchard, WA

I like the effect in some images. Slow shutter speed effects can be fun.

Moondoggie Loc: Southern California

Great looking photos, even at a slower shutter speed.

Dalbon

It doesn't make any difference about the tripod movement or the slow shutter speed because you can always change that next time but I like what you've shot here. Little different but still you did good.
David

AzYooper Loc: Sun Lakes AZ (Almost Phoenix)

I have found that balconies on buildings are not as stable as one might think. Same for bridges. Perhaps your own movement could cause the balcony to vibrate slightly.

home brewer Loc: Fort Wayne, Indiana

I like these. I think the slow shutter caused the great shots, Also i think there is camera movement. But like i said I like them more than most firework shots.

PhotogHobbyist Loc: Bradford, PA

I'm in agreement with several others, looks like camera movement. I've had fairly good results with hand held and shutter of 1/30 to 1/15 second and aperture of 5.6 to 11, and ISO 200 to 400. That is not to say those are the best settings, but I have had some fair to good results with them.

Sidwalkastronomy Loc: New Jersey Shore

I know from my telescope viewing setting on a deck can have a lot of vibration from minor walking around. In backyard observatories the telescope pier is always isolated from the floor

davidrb Loc: Half way there on the 45th Parallel

Your last shot is indication of something you need to re-examine, your tripod techniques. Flaming embers do not fly in the manner shown, they travel very fast in straight lines. The sensor that recorded this image was not stationary. You're also leaving your shutter opened too long, but that is technique you will find easy to master. Different shell patterns require different timing, again an easy skill to develop. You do have what you need in equipment, desire, and attitude. Experience is difficult to achieve if you wait for fireworks. You can gain experience and do some experimenting if you want by practicing shooting vehicles on a busy road at night, without overhead lighting. Very similar circumstances to fireworks and usually easy to find. The most difficult technique is focus. The lights on vehicles in the USA will serve as perfect props on which to practice. Doing this will also give you a sense of timing similar to fireworks. Freeze a vehicle so its license plate is legible and you are ready fire fireworks. Have fun with it!