Contrary to popular belief, more megapixels do not equate to producing better pictures. Unless you intend to make prints larger than A3-size, a camera sensor with 5 to 8 megapixels would be more than sufficient.

The benefits of having a camera with a high resolution is that if you're snapping images of a tree, having more pixels in an image would mean you would be able to capture the leaves in a greater detail. Therefore if you're cropping an image, you can do so without losing too much in terms of sharpness.

However, do note that sometimes having a high-megapixel sensor may not be wise. This is because too many megapixels could produce noise and artifacts in images captured at high ISOs.