Here are my tips... I'm making the assumption you are new to photography. If not, you can ignore this
#1 Get a good DSLR Book (e.g. DSLR for Dummies)
#2 If you got a kit lens, ditch it for something that shoots down to f/2.8.
#3 Get good photo management software: Adobe Lightroom or Apple Aperture
#4 Ditch the Canon strap (I like Domke or Gordy's straps)
#5: Get an extra battery (Adorama.com has cheap ones)
#6: Get the fastest memory cards you can buy... I prefer a few smaller/faster cards over one big one.
#7: Get a prime lens to see what it can do (50mm 1.8 is a great place to start for just over $100... and you will find over time, your favorite photos were taken with this lens)
* Get in close... closer than you naturally would.
* Get down to eye level... if you are taking photos of children, on your knees. If you're taking a photo of a dog, on your elbows.
* Move. Don't just take a photo where you are- move around to see how the perspective changes. Oh, and get in close.
* Isolate. If you can see someone's head in the shot... then if their feet are also in the photo, it will be boring. Get in close.
* Learn to set your white balance for every shot... this will dramatically improve your images (or shoot RAW and do it in the software above) Or better yet, do both.
* Take lots of photos, and learn to delete 9 out of 10... the secret to being a great photographer is to delete the thousands of boring or bad photos before anyone ever sees them... only let people see your great ones.