Here is a great tutorial, including video. Once you do your first room, you'll never have the courage to pay for someone else to do it. It is that simple. Messy, but simple. :) Good luck!
https://lifeonsummerhill.com/painting-a-room/ Here is a tutorial I created on my website that will help.
Here's a great paint guide! https://www.clare.com/blog/paint-tips/how-to-paint