Richard Dansky has a good post about writing about writing. In seven questions he covers quite a lot of territory.
If there's any one idea that I need to think about more, it's question #6
6-There’s so much good information on writing out there! How do I narrow it down?
Here’s a useful guideline: If you spend more time reading writing about writing than you do writing, you need to cut back. If you produce more tweets of links to articles about writing in a day than you do words, you need to cut back. If you have spent more time laying out plans for a blog you intend to write on writing but will never actually do anything on than actually writing, cut back and punch yourself in the back of the head a few times for good measure.
A good rule of thumb is to read until something sparks an idea and makes you want to write something of your own. If, over an extended period of time, nothing does that, you may want to ask yourself why you’re reading about writing, and instead turn to blogs and podcasts about golf, cooking, Bigfoot hunting, or making your own cheese from common household chemicals.