First of all, don't use flash. The first time you try shooting close and forget to turn your flash off, your subject will look like a big, white, shiny blob. Children might be fascinated by the ghost you took a picture of, but you probably won't be. Occasionally, if you happen to have the right angle and are slightly farther away, you may be able to get a good picture with a flash but it's better to have good natural lighting.

2) Use Your LCD Screen

Then next thing you want to remember is to use your LCD screen instead of your viewfinder. The LCD screen sees what's going to be in the picture while the viewfinder is slightly offset. This isn't noticeable when you're taking pictures farther away, but up close you end up having a picture of half a flower or a headless lizard.  

The picture on the left was taken using the viewfinder. The picture on the right was taken using the LCD screen. Notice the difference in lighting and focus as well as that the subject is barely inside the frame.

3) Parallel Shooting

At a very short distance from the subject, it is sometimes hard to get the entire subject in focus. One tip is to angle your shot so you are parallel to what you are shooting. Obviously, most things aren't flat, but lining us the shot parallel to the main focal point of the shot will help make the largest portion of the shot clear.

4) Use A Small Aperture Size... And A Tripod

Next, it's best to use the smallest aperture size (largest F number) possible. Using a small aperture allows more of your picture to be in focus. The problem with this becomes the lack of light. The smaller the aperture, the less light that gets in and the shutter must be open longer, making your picture more likely to be blurry. When shooting really close, the smallest movement when the shutter is open can turn into big blurs. It's best to use a tripod if you can, and if you can't fit a big one where you're shooting get a small tabletop tripod. They're inexpensive and much easier to move and use than the traditional monsters.  

The picture on the left was taken with a large aperture size (f 2.5). The pictured on the right was taken with a small aperture size (f 8.0). Notice the difference in the clearness of the orange ball inside the green one.   Click on the images for higher resolution photos.

Picture on left was taken without a tripod; the picture on the right was taken with a tripod.

5) Blur With A Larger Aperture

Now if you're up for experimenting, and you've used the last tip, try this: ignore the last tip. Try blurring part of a picture by using a larger aperture size. While a picture can be great in focus, you may also want to try having part of the picture out of focus. Remember, always make the part that's in focus be the main subject of your photo, but adding blur to other parts can make a great shot. Having only the main part of the object in focus can give the picture an artsy feel. Having a background that is out of focus can also make your subject stand out more. Just keep trying different things and see what you can get.  

The blurred background allows the flowers in the foreground to stand out more.

6) Experiment

The last tip, which applies to all photography, is to remember to experiment. While changing the angle just slightly in a landscape picture makes little difference to the final product, doing it with an extreme close up can provide an entirely new picture. Many of my flower shots are close ups from above the petals of the flower. But some of my best shots have come from different views, such as from the ground pointing up so you can see the transparency of the petals, or from putting the camera inside the folded petals of the flower.

Flower on the left was taken with the camera pointing up giving the flower petals a translucent appearance.  The flower on the left is an extreme close-up shot of the inside of the folded petals of a flower.

Try new things, and also remember to always try new subjects. You may have seen something every single day, but have never really looked at it close up.