if you host it at photobucket.com they have a nifty edit feature where you can reduce the image size with a click of your mouse. or you can open your photo editing software (photoshop, whatever) and click image, image size, and reduce the resolution that way which will make the picture smaller.
i just put mine into paint and go to "images" the scroll down to "stretch/skew" then I type in 50% and 50% and hit enter. Then it'll be smaller. Then i usually dp it one more time after that, and it's small enough.