There are seriously some amazing people on Google Plus who are helping average users get better at the Plus game. One of them is +Simon Lausten who created the Google Plus Cheat Sheet. He has so far created two cheat sheets, one is a full of shortcuts and other has helpful tips and tricks. His cheat sheets have been translated in over 20 languages.
Here is the English version:
For other languages of this cheat sheet visit Google+ Cheat Sheet 1
For other languages of this cheat sheet visit Google+ Cheat Sheet 2