10 Quick Macro Shooting Tips

1. Check focus: When shooting at 1:1 or higher magnifications, depth of field is extremely narrow. Make sure your camera's diopter is set properly for your shooting eye, and triple-check focus before shooting.
2. Check focus again: After you shoot, if you're using a digital camera, check the image in your LCD screen and zoom into it as far as your camera will let you to confirm that your subject is in focus.
3. Eliminate subject motion: If you're outside shooting a flower's stamen or any other high-magnification foliage, the slightest wind will not only mess up your composition, it will blur it. If possible, plant a stake in the ground and tether the flower to it to add stability. Use the fastest shutter speed you can get away with. If you are shooting at a small aperture, a ring flash or a pair of lens-mounted flash units is necessary.
4. Eliminate camera motion: You can control composition and eliminate the variable of a moving camera very simply: don't move it. Put it on a tripod, a bean bag, or a mini-pod so it goes nowhere.
5. Don't curse the darkness, add a flash: In studios, you can control all of the above variables and use any light you desire (hot lights, strobes, HMI, etc). But in the field, you don't have control of the light. One moment you may be shooting in bright sunlight, the next under the dark canopy of a forest. It could be sunny or cloudy. The solution is to bring your own light -- either a ring flash or a two-flash, lens-mounted setup. This way you can also stop down for greater depth of field and sharper focus. Want backlight? Bring a pocket slave. Overhead sun causing harsh shadows? Diffuse it with a translucent white umbrella.
6. Eliminate background clutter: Remember that the eye naturally goes to the brightest spot in a photo, so if you are shooting in mixed light, be aware of what's in the background. You may need to change your point of view, get closer and fill the frame with your subject, or bring a sheet of plain paper or an 8x10-inch print of generic, highlight-free foliage to hold behind your subject. You can also control background clutter by shooting at wider apertures, which reduces background focus, or using a ring light, which throws most backgrounds into darkness. 
7. Eliminate foreground clutter: If you're shooting through dense foliage to get to something of interest, make sure this doesn't block your view. If permissible, trim away blocking branches or leaves. If not, try to find another angle. Still no good? Move on.
8. Eliminate poor exposure: Be especially conscientious about metering and exposure when using a bellows or extension tubes and a handheld meter. The greater the distance between the rear element and the recording medium (film or sensor), the longer the exposure or wider the aperture. If your camera has TTL (through the lens) metering, you can relax -- somewhat. Bright backgrounds can still mislead the meter, so bracket. Shooting digital? Check your histogram to confirm exposure's right.
9. Eliminate grain and digital artifacts: With so little light reaching your film or sensor, you may be tempted to use fast film or pump up your digital camera's ISO setting. Don't. This adds grain or digital artifacts (also called noise), which is an unwanted distraction. The grain makes the image appear less sharp, which defeats the purpose of using a super-sharp lens at a smaller aperture. Use your digital camera's lowest ISO setting, or a fine-grained film like Kodachrome 64 or Fuji Velvia, and add a tripod or flash to make up for the loss of light.
10. Eliminate bland subject matter: Be bold in your composition, look for stunning color, and don't be afraid to experiment and create abstractions. The greatest benefit of Macro is how it transforms mundane subjects into worlds of wonder by enlarging them far beyond what the human eye is used to seeing. Pump up your digital camera's color and contrast settings if that suits the subject. With a film cam, use super-saturated film.