Maximize your storage space
Most cameras come with a very small memory card. Upgrade it to something larger, and keep the old one as an emergency backup. You can fit more pictures onto your card by lowering the resolution or increasing the compression that the camera uses. Even if your camera has a high megapixel rating, you can manually set it to take slightly lower-quality pictures. You should still be able to make average-sized prints with little to no loss of quality.