Here is a video by Joe Allam talking about some basic beginner mistakes to avoid in your photography. Here the are five areas covered:
- Uneven horizons can be very distracting. You can fix this in post or pay more attention while you are out taking pictures.
- Get your white balance accurately by setting your camera to auto white balance or match the white balance setting to the light source. Carrying a grey card is also a good idea.
- Use the right aperture and shutter speed to make sure the subject is in focus. Blurry or unsharp images can look very amateur. Avoid camera shake by using a tripod if necessary.
- Pay attention to your composition by focusing on symmetry and not cropping at odd points.
- Use auto exposure to get the right exposure under changing lights and do not be afraid to use aperture priority or the built in light meter of your camera.