I found a couple of excellent tools to help with the self-editing process.
The Blood Red Pencil is a blogpage run by professional editors. I can't remember who recommended it, sorry. It's chocked full of useful tips and advice about what to do, and what to avoid doing, when preparing the final draft of your work. I've added it to my internet favorites.
I found Self-editing for Fiction Writers, by Renni Browne & Dave King, in Barnes & Noble. It covers the same kind of things, but in a more structured way. I'm only about a hundred pages in, and already I've found plenty of invaluable insights about characterization, proportion, and point of view.
Part of me is excited at finding all this great advice, the other part is gutted, because now I have a lot more rewriting to do.
Ah well, back to the drawing board.