Answer:
If you haven't yet taken the pictures, if you can alter the camera settings for the size of the photo to be taken to the lowest possible size and quality.
If you have already taken them, download them to the computer and alter their size by or a suitable propriety program if you have one, or freeware programs such as "PictureTray" or "Photo Resizer". See the related question.
(Of course, you could always crop them , but make certain you always work on copies).