He also started as a pretty mediocre player and now deserves his rank among the best players! He shares a lot of his secrets and is also #1 commentator now for AoE II:DE related games: https://www.youtube.com/channel/UCZUT79WUUpZlZ-XMF7l4CFg
Also watch his Twitch account.
Spirit of the Law is also a great resource: https://www.youtube.com/channel/UChzLZJo-SxuPHz-oYKAIC_g