Find a goal you love or care about and either find a project that shares the same vision as yours, or just create the project from scratch and lead it.

Open sourcing your work is an important part of learning as people will eventually send you pull-requests or report issues to you.

Pairing is one of the best way to get up to speed. Joining a company that believes in pair-programming is important, but you might also want to find a pair for yourself (and open source projects could provide you this opportunity).