Set the camera's resolution to take high quality photos at the highest resolution possible. Low-resolution images are more difficult to alter later; it also means that you cannot crop as enthusiastically as you could with a higher-resolution version (and still end with something printable). Upgrade to a bigger memory card. If you don't want to or can't afford to buy a new one, then use the "fine" quality setting, if your camera has one, with a smaller resolution.