Super Structure: The Key to Unleashing the Power of Story by James Scott Bell Take Off Your Pants! Outline Your Books for Faster, Better Writing by Libbie Hawker Story Genius by Lisa Cron Wired For Story by Lisa Cron Save the Cat by Blake Snyder (for screenwriting but has excellent information that applies to writing a manuscript as well) 100 Ways to Improve Your Writing by Gary Provost (lots of great writing tips. You have probably seen the popular tip about varying your sentence length - this is page 58 of Gary's book). The Emotion Thesaurus by Angela Ackerman & Becca Puglisi (All of the Thesauruses by Angela and Becca are excellent resources for writers) The Emotional Craft of Fiction by Donald Maas Understanding Show Don't Tell (And Really Getting It) by Janice Hardy Fight Write by Carla Hoch: How to Write Believable Fight Scenes
Resources to Find Agents
QueryTracker: Agent search engine. From here you can find agent websites, Twitter accounts, and much more.
QueryTracker Newsletter: QueryTracker's agent alerts newsletter, provides updates on new agents, agents that are opening back up after closing to queries, and more. AgentQuery: Agent search engine. Writer Beware: (warnings about bad agents and publishers)
Additional Resources
Writing with Color: A Tumbler post on why writers shouldn't use food to describe people of color. It also has a Part II that provides excellent examples of how to describe people of color.