A number of your photos, intentionally or not, use depth of field.
I'd read up on DoF and find out how to adjust your camera to get "just that field" depth for a particular photo.
Take shots. Lots of shots!
BruceH - Go get "Understanding Exposure" by Peterson.
Worth a $1,000 lens, all by itself. (And I learned more from it that my first Photography class at the local Jr. College.) Read it before Everest!!!
Do the monthly Photo Challenge on this site or try the monthly Photo Assignments (also here).
I took a basic photo class once and one week we had to set our camera to Av and take just Av shots all week (a minimum of 36 shots, or a typical contact sheet), the next we used Tv, next was DoF...
Try a community college to get the basics and then go from there. And the folks there tend to have lots of suggestions and generally know the area and what's available.
Find a nice camera store and check out their inventory.
I thought I wanted a backpack but ended up getting a slinger. Am very happy with it. (Don't carry the laptop in it.)
I've got a Canon 17-85 mm EF-S f/4-5.6 IS USM Lens. Have had it for a while and never noticed any problems. Now, suddenly, I seem to be getting a lot of chromatic aberration.
Got me bugged.
Any ideas?
Somewhere during the past 5 years or so it suddenly dawned on me that there are people out there who have a singular passion. They focus a majority of their time, money and effort into that one thing, and in many cases either seem to be better off for it or happier than the rest of us, or...
Come back and tell us how you feel about it after about 1,000 or so shots.
(Sounds like you already got the bug. )
I love my 40D. They'd have to pry it out of my cold, dead hands. (Take a picture. It'd be easier!)