Ok, assuming you are talking about the new iPad with the 5MP camera, grainy photos are probably a result of poor light. Every sensor has a little electronic noise. If there is not enough light to override the noise then the noise also gets recorded as part of the photo; resulting in a grainy look.
To avoid noise make sure you have plenty of light. Indoor pictures are always tricky get well lit. Turn on some extra lights, open the windows, or move the subject next to a better light source.
Hold in mind that artificial lights may cause color casts, though newer cameras are getting much better at detecting and adjusting this. Incandescent lights can cause a warm yellow/orange cast. Florescence can make things greenish. The newer (supposedly full spectrum) lights often leave things a bit cool (blueish).
The Enhance tool in the Photos app will usually correct this; or you can use one of the many photo apps available.
Hold in mind that what your eye thinks is plenty (especially when you've been in a room for a while) may not be enough for the camera. Eyes are considerably more adaptable than cameras.
Ok, that's more info than what you asked for, but I went into ramble on mode. Just remember, if the photo's are looking grainy, try to increase the amount of light.