Your pictures are nicely composed and the color is well saturated and seems accurate.
I do see some softness in some of the shots and that may have to do with the 550's reputation for focus issues and/or conservative sharpening in-camera. In the shot with one of the bugs, it appears that the stalk of the plant is more sharply focused than the bug and I am not sure whether that is the effect you intended.
You can correct DOF issues by using the M setting or the Aperture Priority setting and using an aperture setting that produces sharpness across the board. I find that F8 or larger usually gives me a sharply focused picture, though I say this from working with other cameras, not the 550 (my own 550 is due for delivery today). I also know that camera lenses have sweet spots where you get the best results.
Folks around here recommend using spot metering for better results. I also play around with focus lock/exposure on one area and then recomposing the shot. I believe the 550 will also let you change the focus area manually, though someone else will have to describe how to do that.
A very nice start. I look forward to seeing more of your photos.
EK
Nikon D70s, Panasonic TZ-1, Fujifilm F30, and Olympus SP550
