I’m looking for some updated guide to learn how to play better
I know the one on ESOC (ESOCommunity - Strategy Wall).
It is not updated for the last patch with all the new cards, but is great to improve your gameplay. It contains many decks and BOs written by pros.
Other than that, there are nice videos von youtube, both educational videos and recent pro matches.
And if you have any question, you can post one on this forum, the aoe3 community is overall friendly and happy to help.