I just went outside to take a snap shot with tripod and whatnot... Problem with mine is the huge crop I had to do and the lens itself isnt the sharpest...
I used my 75-300 and it barely used any of the frame. Wish I had more MP and possibly a bigger zoom and sharper lens, to get an awesome shot... I tried some sharpening in PP but the image was just too small (from large crop) to really do any good.
Well, I think you could have done alright with your setup to be honest.
First, stop the lens down to its sharpest aperture, probably like f/8, maybe f/9.
Shutter speed will be like 1/125, for a good moon exposure anyway.
Next, enable mirror-lockup - not sure if your Rebel does this, my setting is in my 'custom functions' menu.
You'll want to manually focus while in live view (not sure if you can do this) where you can enlarge the area you want to focus on at 5x or 10x zoom on the screen. Then use the self timer to get a steady shot (or a release/remote).