Buck Woody has a great post on learning how to learn:
In this new world of fast-paced learning, you’ll often find that you have to “throw away” what you’ve learned, meaning that a new language or tool is out now that requires your attention, and you won’t return to the one you know now. That doesn’t mean your hard study was wasted, because you’ll often find that new technology builds on the one you just learned, but I find that Type-A technologists are loath to drop something they just learned. You’ll have to get over that – it’s the way it is.
However, it can be true that once you learn something, it may be in an area that you just had to come up to speed on quickly, or it has “staying power” and will be around for a while. In that case, take this same process, and repeat all the steps, taking time to fill in the gaps and go much deeper in the areas you didn’t spend time on during your speed learning.
I really liked this post. The first thing it reminded me of was Sir Francis Bacon’s Of Studies (pdf, but with bonus content from Samuel Johnson), specifically the part about how we should superficially breeze through some books, but that others we must digest. The same goes with technologies.