May I make a silly writerly suggestion, from someone who loves her outlines?

Get someone to look the outline over for plot holes and flow. I didn't do this for the unicorn book and needed to write a new ending; I did this for Skywatch and was presented with new opening and penultimate scenes, which vastly improved the book before I ever started. It had never occured to me before to get someone to look over an outline, but it helped so much!

(As always for writerly advice, Your Milage May Vary.)