A little advice if you want to get into flying drones for personal or commercial use.
Buy a cheap one to learn how first.
For a more advance drone you will need to understand the functions thoroughly before flying it Once you feel like ready to fly, make sure you are in a safe place, and its not too windy or raining outside.
Remember there is a limited amount of battery life, so whenever you fly it, for whatever purpose or video footage you want to get, it will have to be done quickly.
The videos for compass calibration can confuse you, there are several youtube videos, make sure you find the one that works for your drone.
Don't be discouraged if you have trouble at first, it takes time, as long as you don't destroy your drone completely you can always try again. don't learn how to fly near a body of water, if it goes in that may be the end of it, I made that mistake and that's why I physically grabbed it as soon as I was losing control (in the video)
Enjoy peeps, hope I may have helped someone.