Here’s a great slideshow with tips from National Geographic on how to take macro photography. Here’s a few tips:
Tip #1: Macro photography is photography magnified. It is generally recognized as “macro” when you are increasing the size of an object in your picture from about half life-size, as represented on the image sensor, to five times life-size.
Tip #2: As a general rule you should use an f-stop no wider/larger than f/16 to get all or most of the main subject in focus. If you are photographing a subject that can’t be arranged more or less on the same plane, you will have to decide which parts of it you want in focus.
Tip #3: Get creative with macro photography by shooting the subject from an unexpected angle. Try different lighting, as well, using front lighting for deeper color saturation and side lighting to highlight texture.
Tip #4: Autofocus doesn’t always work well when shooting extreme close-up photography. Switch to manual focus and you’ll get more consistently sharp macro pictures.