Zembrin 

There are many factors but an understanding of composition and what camera settings affect lighting and thus the image: 

- Aperture: how wide the lens shutter opens to let light in. 
Wider = more light, higher exposure and more apparent distance between your subject and background, where your bg may even become blurry. Narrower = less light, lower exposure and less apparent distance between your subject and the background. 

- Shutter speed: how fast the lens shutter opens and closes. 
Faster = less light but can more successfully capture movement crisply. Slower = more light but can lead to more blurry photos depending on speed of subject.  

E.g if you're shooting a sports game during the day you can increase the shutter speed to avoid blurred images, knowing that you have sufficient light. If you're shooting at night, you'll want to reduce shutter speed to increase exposure, and opt to shoot slower subjects for a crisper image. 

-ISO: artificial exposure produced by your camera. 
This should be at the lowest setting and bumped only if you need more light to reach proper exposure. High ISO leads to noisier images

Better camera equipment allows you to more easily manipulate these settings (amongst others ) and produce higher resolution images.