I agree with LizardKing. Additionally, I think the Rule of Thirds isn't the final word on all compositions; I firmly believe it's more of a guide to help one visualize and consider alternatives during the composition process. But working with that guide would have helped some of these photos, notably 1, 2, and 3. So, it's something you might consider.
#1: Dead center, shot from above, too much dead space, all take away from what is a beautiful flower. Try getting a lot closer and shoot it from an angle or even underneath, but try to avoid cutting off petals. Well, play around with it, anyway. Get creative with flowers. Nearly everyone photographs flowers at some point, so it's easy to get bored with the same treatment over and over.
#2: I like this image. The only thing I'd do is crop it closer, perhaps rotate it 90° CW, and poke at the colour and curves a bit. It's clear the moth is crippled and dying, so I'd try to emphasize that. I use an 18-55 lens, too, and I see you did something I also do in my close-up shots: set the f-stop too low and miss the focal point. At f/5.6 at 55mm your DOF is very narrow, and here you've really got only the trailing wing in-focus; I assume you wanted the moth's face to be the focal point, but it is OOF. So, either keep trying to nail the face or go up a stop or two and get a wider DOF. Here's an edit that I think shows a bit more of the moth's plight and has a bit more drama, perhaps:
View attachment 14728
#3: Same thoughts as in #1. Also, the horizon seems severely tilted; that effect is rarely done well, so I'd tread carefully there.
#4: This is really cool, and a fine example of when dead-centering actually works very well! There's wonderful texture and tone in those lamps. I love the colour and the shadows. The white balance might be a little off; it's difficult for me to be sure. And there's a stray spider web on the base of the left lamp that could be cloned out as it tends to distract. But this is a splendid photo. Great work!
I wouldn't consider these to be "snaps" at all.