Shortcuts
Here are some shortcuts making your life much easier:
Cmd + Shift + a
-> Quick action, much faster then navigating menus
Cmd + l
-> Goto line
Cmd + j
-> Shortcut templates (like eco + tab), really handy! You can even create your own! Don't type, be smart!
Cmd + (Shift) + n
-> Open Class or Open file (most important!)
Cmd + F12
-> QUICK outline the methods in the file
Cmd + H
-> History, quickly navigate between last files used
Cmd + up and Cmd + N
-> Navigating without project explorer and creating a new file in the current folder!
There is also a nice cheat sheet by JetBrains you can find here.