Taking silhouette shots can be as easy as pointing your camera at a subject and simply pressing the shutter button, or as intricately challenging as any other form of photography.
Taking into account the subject you are photographing will give some indication of the equipment you will need to complete the task. So being fully prepared will certainly help achieve results.
How equipped are you?
You definitely don't need a special kind of camera to take silhouettes successfully, but as is usually recommended, the trusty old tripod is fairly essential, or at least have something suitable enough to stabilize your camera against induced blur or camera shake.
A lens hood would certainly help to eliminate lens flare because more often than not, silhouette images will be taken towards the light.
A graduated grey or neutral density (ND) filter will help to cut down some of the background glare. As they do drop the light ratio.
You may want to use some form of flash (not too much or you could spoil the effect) to lighten some foreground elements, because shooting into the light will not only darken your subject, but also the foreground can suffer.
Lens type is not critical, but the zoom you use for general use should suffice.
Shooting towards the light can result in a shot with a somewhat monochromatic look and you may decide to shoot silhouette in black and white but a little bit of colour does add interest to these images.
When we think of the word 'silhouette', we see in our minds jet black figures, or shapes, on a very palish, or white background. However, it is aesthetically more pleasing to the viewer's eye if there is a certain amount of detail to be seen in the subject matter itself. Hence, that little bit of fill-in flash is handy. How much flash to use, if any, will be dependent on the amount and direction of the background light source. Try not to have too much of the image blacked or whited out. These areas on a photograph are known as 'negative space' and can be unproductive in an image.
What are the best-suited subjects for silhouettes?
I think anything that carries a strong visual element or is mood invoking, but something that the viewer can immediately relate to. such as the human form, animals like dogs or horses, for example. Trees, such as palm trees, or Pandanus trees, can create good moody scenes. Jumping Motocross riders can bring about dynamic action shots. And don't forget to make the decision as to which way you should hold the camera to take your shots, portrait (vertical) or landscape (horizontal) mode. If unsure, try a few shots either way and make the decision when you see the results.
try to have your silhouette subject/s stand out alone from other elements in the scene, or if there are two main subjects, it is best to keep them apart so that each subject is a separate entity and stands out from the other.
See also "Backlight Photography"