There are various factors that come to mind when buying a digital camera. When you are investing thousands or rupees or dollars or euros for a camera, you want to make sure you don't buy a model that doesn't really suit your purpose or is much too advanced for your requirements. I listed two of a few pointers that may assist you in making the right buying decision.
CCD or CMOS?
CCD (Charged Coupled Device) and CMOS (Complementary Metal Oxide Semiconductor) are the two types of image sensors used in digital cameras. Cameras with CCD sensors are recommended over CMOS plainly because the image quality is tremendously better in the former. Though CMOS lenses are significantly cheaper to manufacture and easier to implement than CCDs, the difference in image quality is simply passable.
CMOS sensors are extremely portable and require considerably lesser battery power - precisely why their most common application is in webcams and phone cams.
The Megapixel myth
First things first - higher megapixel count is in no way a measure of the quality of your pictures. Quality is determined by the image sensor; megapixel count simply denotes how big your image would be. For any home user who wants to post snapshots on the Internet or print them on a maximum of an A4 size photo paper does not need anything more than a 3-megapixel camera.
Though the megapixel count does not directly relate to image quality. It is noticed that the higher megapixel cameras have more professional features, hence they are generally more expensive.