Look at samples of photos similar to what you want to take. Figure out why you like them, and try to duplicate what you can. Learning about how to control your camera will help you a lot.
Learn about shutter speeds. They help you get clear photos, especially when there is movement, or low light levels.
Learn about lens openings. This helps you control how much in focus your foregrounds and backgrounds will be.
Understanding composition will help you make your photos more interesting and pleasing.
Be very thoughtful about what is in your photo and what you want to keep out of it.
Lighting also has a big effect. Observe if the lighting looks good or unflattering. If it looks bad, then move to a different direction or location. Direct sunlight is often too harsh in the middle of the day. Try the shade, or just turn them away from the sun. You can use reflectors to add light.
Posing can be challenging. Study poses from other photos, or poses of the character you will be photographing.