1. The TV Writer's Workbook by Ellen Sandler
    It's full of creative and often fun exercises for writing a spec episode. What I liked best about this book is the tone. So many authors of writers' guides adopt a smarmy "if you make this mistake, you're an idiot" attitude or muddle their points with gratuitous jokes. Sandler is clear and straightforward yet understanding.
  2. Paul Feig's "Freaks and Geeks" Character Bible
    The show blew my mind when I was thirteen, and the funny, thoughtful character descriptions are what I aspire to with my own character crafting. Each one leaves me thinking "I know exactly who this person is."
  3. Ken Levine's blog
    Veteran TV writer Ken Levine frequently and generously posts great advice for aspiring TV writers. I bookmarked his posts from 3/13/13 (how to draw comedy from the premise rather than the jokes) and 8/2/14 (he deconstructs Mike Nichols' tip that "Every scene is either a fight, seduction, or negotiation.").