One of the most important things in photography is composition. There are a number of tips and tricks that have helped me in learning to take better (wildlife) pictures. I've tried to describe some of these tips and tricks illustrated with pictures in this topic. These tips and tricks apply to point-and-shoot and SLR camera's.
Most people put the object they're photographing in the middle of the picture. While this may seem an obvious choice as most camera's only offer a centre focus point it's not the best composition you can think of. If you put the main object in the middle of the picture the result will often be an uninteresting picture. As an alternative try to divide the picture in thirds both horizontally and vertically and place your object either on the lines, or on the intersection of the horizontal and vertical lines. The lines that make up the thirds can also be used for placement of the horizon. If you usually place the horizon in the middle of the picture try putting it on one of the horizontal lines, you'll be amazed at how different the picture will look.
In both of these pictures the frame has been divided in thirds. In the leopard picture I've intentionally put the face of the leopard on an intersection of the lines. This makes a very attractive picture without any distracting elements. In the picture of the foam nest frog I've done something else; in this picture I've put the frog right of the first vertical lines of thirds and filled the other third of the picture with the tree.
A thing a lot of people (including me) often forget is giving some thought to the background of pictures. When you are taking pictures you usually want the background to be as non-distracting as possible. It's not often that I post bad pictures that I've taken, but for this topic I'll make an exception
I'll illustrate the background issue with three pictures which I took of a foam nest frog:
The first picture is an unattractive one as the background is almost completely white, it distracts from the object of the picture. The second picture is slightly better, but still the top right corner of the picture is too light and distracts. In the third picture I finally got it right. I used a tree in the background to get a dark background. Due to the used aperture (f/8 ) the frog is sharp and the background is blurred.
Get down to subject level
Always try to get down to the eye level of your subject. This is not always possible because a lion might not take kindly to you lying on the ground in front of him, but do your best to get as close as possible. Often it's better to park your car some distance from a sighting and use a bigger zoom than parking next to a sighting and using a small zoom. If you park some distance away the angle between you and the subject will be smaller than if you're parked right next to it. Due to the smaller angle using a large zoom it will appear you were at eye level when you took the shot.
In the image of the lion and the tortoise you can see the effect of using a long zoom when standing some distance from a sighting. In both pictures it looks like I was lying on the ground when I took this shot, but believe me I wasn't.
If you're taking pictures of small (slow) animals don't be afraid to get dirty and lie down on the ground to get your shots. Here are two examples of pictures I took of a scorpion, one from above and one from lying on the ground:
The difference in the two pictures is evident, the one from a low perspective is much more interesting than the one taken from a high perspective.
Lying on the ground you have the option of taking a close-up or a wide angle picture:
These pictures are as different from each other as the scorpion ones, but they were all taken at eye level.
Once you've mastered all these techniques feel free to do is to break them
All the techniques will help you take better pictures but once you know when (and why) to break them you'll get the occasional great picture. Often it's the little things that really make the difference between a nice picture and a great picture and luck is a factor in wildlife photography.
I hope this helps you in getting (even) better pictures. The best advice I can give though is practice, practise, practise.....