I love macro photography and I want to share my experiences with you.
1 - Use a tripod. If you dont, then shoot in manuel focus mode , since your movements will destroy the AF point as your body moves.
2 - Sometimes you can use a ring flash. But not always. It can cause sharp awesome shady areas behind your subject. Usually dentistry images are captured with a ring flash where a human being is in the business. But in other macros I use my flashguns and soft-boxes.
3 - Be creative. Everything has a detail for a macro shot. If you have time then try funny things. Look around and I bet you are going to see too many thing for macro photography
4 - Since macro show every little detail,you have to take them into consideration too. Be clean. Otherwise fuzzy things and dust will be the heroes of your image