Hey all, first time in this sub-forum. Great tips and advice. Here's my two cents:

Get involved with a local club or association and help build/maintain trails. You can learn a lot from riding them, but you'll go one step further when you learn to build them. You'll start to recognize aspects of terrain and technical stuff and see better lines. Not to mention, you'll be rubbing shoulders with riders that are better than you and you'll pick up on things.