White balance and exposure settings are very important when taking a panoramic photo. This is why we warn against using the "panoramic" setting on your camera if it has one. With many cameras, the auto setting doesn't lock down the exposure and white balance, which means it could vary from photo to photo. And then once you stitch the photos together, it will look uneven with visible "seams."
To manually set white balance, consult your specific camera's manual. However, it usually works something like this: On your camera menu, you should be able to set or evaluate white balance. To do that, point your camera at a piece of white (or neutral gray) paper and press the shutter, making sure the paper fills up the entire lens. Ensure the paper is in the same light as where you'll be taking the panoramic photo. After you press the shutter, your white balance should be all set and locked.
To set your exposure speed, you can use the "P" setting on your camera -- "P" stands for "program mode." After setting it to P, point your camera at the main focus of your photo. Press the shutter down halfway -- this focuses the camera and sets the exposure. Note the f-stop and shutter speed values after you do this. Now, set your camera to manual mode (usually "M"). Set the controls to the same f-stop and shutter speeds you just noted.
Also, don't use your polarizer if you have one. It may result in banding and uneven backgrounds.