Disclaimer: I'm not an expert in these areas, I'm just a regular hacker. You won't become a Rails ninja-rockstar-guru under my tutelage, for example. What you'll hopefully become is a confident beginner who has knows how to learn. Like the old saying:

"Teach a person to hack and they'll hack. Teach a person to learn to hack and they'll gradually become a ninja-rockstar-guru over the rest of their life."