1. Take a lot of photos
Take it from someone who's taken quite a few photos, when you take the time to take a shot, make sure that you take a bunch of them before you change positions. This ensures that at least one of the shots you've taken will be good.
You'll also notice quite a few things that you will want to photograph on your usual commute. The one thing that you have to remember is that once you leave a place, it's going to be extremely hard to get similar kind of conditions again.
3. If you are thinking about taking a photo, do so
Once you start developing your talents, you'll start seeing interesting stuff to photograph all over the place. Don't be shy to whip out your DSLR anywhere to take some pics. I've taken pics of people in the bus, in museums, and pretty much everywhere I've gone without a problem. I used to be self-conscious when I first started doing this, but I'm not anymore. I even whip out my camera when I am teaching when I see something interesting.
4. Take photo sharing with a pinch of salt
While a lot of photographers swear by photo sharing sites, like Flickr, I only use my Zooomr Pro account, which I got free for life, to backup all of the photos that I take. At last count, I had uploaded about 12,000 photos to my account. I don't share any of my photos. It's simply a backup solution.
This doesn't mean that you can learn a lot by sharing your photos, but ultimately I've learned to not rely on random comments that are made about my photos.
5. Blog, tweet, and share your photos
While I don't use the sharing feature of Zooomr or Flickr, I do share my photos through my blog. I can downsize the resolution pretty easily, and I never waste time watermarking them since they are quite small compared to the original files.
Lastly, once you have a DSLR, you should make the point of staging your own photo shoots. What I mean by this is that you should purposely go out to take photos, with a specific theme in mind. For example, you could go photograph a park or a certain building that you saw that you liked. This should not take more than a an hour or so and will definitely help you improve.
[header image by PP Mag, others by Range]