I agree completely with ohenry,
You can have the most expensive equipment available and still take horrible photos. Technique is way more important than the quality of the lens, and with proper technique you will likely take better pictures than a lot of the "L" glass crowd frequenting the forums.
Some things that you may want to consider:
1. If you don't already have one, invest in a decent tripod. Using a tripod may improve your shots if you are experiencing some blurring due to camera movement. Also, I find when I use a tripod I take a bit more time to properly compose my shot.
2. Enroll in a community college photography class, or buy a good book on composition and exposure.