One type of question that keeps coming up on Programmers.SE is how to learn a specific language, given you know several others (usually through a lot of experience or education).

In some cases, however, one might need to get up to speed quickly for a job, or for personal development, or even to check out a hot new platform.

In your experience, what general strategies have you used to pick up a new language quickly? Are there specific aspects of a language you try to focus on when starting cold? What types of resources do you find helpful in this process?