Using AppleScript to lock screen

Getting information from this answer and this answer:

1. Press the Spotlight button at the top right of the screen (Cmd + Space)
2. Search Keychain Access. Open this
3. Open Preferences (Cmd + ,(comma))
4. Check Show Status in Menu Bar
5. Press the Spotlight button at the top right of the screen (Cmd + Space)
6. Search Automator. Select this
7. Create new Service
8. Search Run Applescript next to the Actions and Variables buttons. Double click this
9. Make sure the checkboxes are Service receives no input in any application
10. Paste this Applescript:

tell application "System Events" to tell process "SystemUIServer"
    tell (menu bar item 1 of menu bar 1 where description is "Keychain menu extra")
        click
        click menu item "Lock Screen" of menu 1
    end tell
end tell

Save this Automator as something like Lock screen (note: code in GIF is different!)

To make a shortcut:

1. Press the Apple button at the top left of the screen
2. Click System Preferences
3. Click Keyboard
4. Click Keyboard Shortcuts tab
5. Click Services
6. Find the name of the service you just created
7. Click the blank space on the right
8. Type your shortcut in

Use your shortcut in any application!

OR...:

1. You could buy Alfred
2. You could use Cmd+Shift+Eject

Found this on another answer but an AppleScript that simply contains the following works for me.

 tell application "Finder" to sleep