Shooting with an aperture of f/8 and above will give you a nice depth of field. You'll notice a longer exposure time, so you'll need a tripod or increase the ISO to get a faster shutter time, you'll see more noise/grain especially if you're using the Rebel models, but you'll get a faster shutter speed. If you want to go automatic with a wider depth of field use the landscape setting (usually a mountain). If you need anymore specific help, your camera model important.