If you've been on the hunt for an agent you've no doubt heard of Donald Maass.
Maass has written a number of excellent books on writing and the writing process, amongst them Writing the Breakout Novel and The Career Novelist, the latter of which is now being offered as a free .pdf download.
From the book's introduction:
IT IS THE DREAM OF HUNDREDS OF THOUSANDS, PERHAPS OF millions, to write fiction full-time. This dream has a powerful allure. To do nothing but create, to spend one's working hours in the dream state of one's imagination—who wouldn't treasure that? Making that dream a reality is the subject of this book.
I read
The Career Novelist many years ago. I do wonder how relevant all of the information is given that the book was written in 1996, but, hey, it's a free download, and Maass has a wealth of experience in the literary field. I've no doubt there's a lot of good stuff in there.