CLOSE ALL THE APPS
Command + Q
If you find going to the red dot to close the app is so bothersome, then this is the shortcut for you! By using command Q, you will be able to close the app that you're currently using or refresh your finder app.
CHANGE THE APP IN A SECOND
Command + Tab
When you use command tab, you will see many all the different type of apps you're currently using. This allows you to change the app you are using immediately.
SNAP A PART OF YOUR SCREEN
Shift + Command + 4
By using shift command 4, you will be able to drag and screenshot a part of your screen and it will be displayed in your desktop. Allowing you to use a part of what you're seeing for your project.
GET YOUR WINDOW TO BECOME FULL SIZE
Control + Command + F
If you use control + command + F, you will be able to change some apps that you're using to full screen. Keep in mind that some apps cannot become full screen size though.
CLOSE JUST A TAB? NO PROBLEM
Command + W
If you want to close just a tab instead of a full app, then command w will help you out a lot!