actually, don't go buy the 50/1.8.
it's a fine lens if you don't have any lenses to begin with. The kit lens isn't as good at 50mm as the 50/1.8 is, obviously, but until you have some more experience with composition, etc, I wouldn't necessarily spend more money on equipment.
As your skills and you "eye" improve, you'll be able to figure out what sort of photos you want to take more often than others. You might not really need the 50/1.8 even though it is a good, straightforward, simple lens.
You might want to get a good wide-angle lens instead. or a portrait lens. The optical quality of the 18-55 is actually pretty good as long as the lens doesn't get beat up too badly. It's plastic and flimsy, but optically not too bad. The only real problem with it optically is that it's only F3.5 on the wide end and 5.6 on the tele end. But for example, none of those photos would have turned out better with the 50/1.8, in fact a couple of them wouldn't have been possible. The dog photo would have turned out better, probably. And besides, it isn't like the 1.8 (mark III version, that is) is a sturdy lens. I waited around and got the 50/1.4, which costs more, but is also built like an L-series lens. It's as "solid" as my 70-200L. (but not nearly as heavy!)
Make sure you're taking deliberate photos. With digital SLRs, it's easy to adopt a "just shoot a bunch of pictures and see which ones turn out good" mentality, and the ironic thing is that you might have spend the same amount of time with subject and a film camera and taken 3 photos, but all 3 turn out well, whereas you might not have anything worth mentioning from the digital "more is better" photo shoot.
Obviously, digital offers instant "feedback" and can be a great learning tool, as you can see a lot of what is going on with exposure and focus and depth of field and such as soon as you've taken a photo, and if you're not happy, you can sometimes just adjust and take the photo again.
Enjoy your camera. Experiment. Don't get too wrapped up in "process" and instead focus on the basics: composition, light, color, content, etc. Any schmo can learn how to manipulate stuff in Photoshop, for example (and yes, there's an art to it, but that's a different thing from photography), or go out and buy a 3000 dollar lens or two if they have the time and money, but that doesn't make them a good photographer. Some of the best photos ever taken were shot with a cheapo disposable camera and walmart film. Good luck and have fun!