Making sure that your subject is in sharp focus, in particular the eyes (if it has them), is usually a good idea.
The first and last hour or two of the day almost always throw the most attractive light on your subject. The lower, softer light and warm colors usually make for a more attractive photo than the bright, harsh light of mid day. Overcast but still bright days can be your friend — soft light without highlights that are too bright or shadows that are too deep all day long. Just keep the sky out of the frame.
Think about how the direction of the light is hitting your subject. Often you can get a better photo by moving around to find the angle of light that looks best. This is easier with subjects that aren’t about to flee the scene, but even with wildlife it’s usually better to risk moving to get good light than sitting still and getting unattractive photos.
Take time to think about composition. Does the photo look better with the subject dead center or off to the side? Don’t shoot so tight that the subject is nearly touching the edges of the frame, or is getting cut off by them.
When shooting wildlife, try to get on the same eye level as your subject. A direct connection is usually more compelling than shooting up over head or down at your feet. Don’t be afraid to get dirty.
When working with image processing programs like Photoshop, resist the urge to turn the saturation way up. It’s easy to increase an effect just a little more and a little more until it’s too much. Natural colors look natural.
Don’t think you need an SLR and expensive lenses to make good photos. Compact cameras can yield great photos when you play to their strengths.
Always bring your camera.