A few things you can try:

1. Keep it still! Sounds obvious, but it really makes a difference. Use a tripod when possible, and even when using a tripod, turn on mirror lock and either use a remote shutter or use a two-second delay so your hand doesn't touch the camera when it's taking the shot.

2. Shoot with a higher aperture. Maybe the issue isn't that your photos are blurry, but that your depth of field is too shallow. Shooting at f/8 or higher will keep more things in focus. Experiment to figure out how different apertures affect your depth of field and what stays in focus. Also, for many lenses, f/8 is about the area where the lens will be the most sharp. Of course, shooting with a higher aperture means that you may need a longer shutter speed in low light, so that goes hand-in-hand with the previous tip.

3. Use the "focus zoom" on your camera's LCD and manual focus for super sharp images. Most DSLRs (including Canons) let you hit a zoom button on the back of the camera once the LCD screen is on to zoom further into what the lens is seeing. From here, you can manually focus to make sure your image is sharp. Without using the focus zoom, you might think the image is focused correct, but it actually might not be.

4. Buy a better lens. The stock lens is pretty good, but if you want more sharpness, buy a different lens. Prime lenses typically take sharper photos since there are less moving parts. A great starter prime lens for Canon cameras is the remarkable f/1.8 50mm prime lens. Crystal clear photos, and the price tag is pretty good too.

I used the first three tips when taking this shot. The camera sat on a Gorillapod tripod, and I shot at f/8 and used focus zoom to make sure it was clear. This is actually something I had to teach myself; when I took my first shot, I shot at f/3 and it wasn't clear at all. I bumped up the aperture and it still wasn't clear. Turns out the camera autofocused on the wrong part (didn't focus on my face). I focus-zoomed in, fixed the focus manually, and I was set.

PS. It's probably not called "focus-zooming", but that's what I call it. No idea what the technical term is.