Things to remember. We're talking about cellphones, not $4000 DLSR cameras. Don't expect miracles. However, with a little bit of knowledge you can make the best out of your camera.
Step 1: Clean Your Lens
Step 2: Framing!
Different angles/ point of view.
Rule of Thirds.
Find the Light
This idea applies to seflies too!
Take candids. Be ready.
Chose where to focus. Be in charge of your camera.
Don't over edit! Please!
Do whatever you want! It's your art!