A successful trip usually starts with a destination. We seldom just pile into the family automobile and pull out of the driveway or head down to the airport to board a flight without a known destination in mind. It could be something as simple as a trip into Shasta to the supermarket, or it might be that we're starting out on a trip around the globe. The fact is that those directionless Sunday afternoon drives that the family used to take when I was a child are things of the past. Today, with time and gasoline so precious, we usually know exactly where we are going and have a MapQuest printout right beside us.
If you are stymied a bit with your story writing, I'm going to suggest that you consider starting your next book with your “destination”...the ending...the last chapter. There's nothing quite like knowing the final outcome of your story...how the main characters solved their issues, how the plot resolved, etc. If you have a clear understanding of the resolution or conclusions you are planning to reach in the final moments of the book, conflicts will often be clearly evident between an earlier chapter you are writing now and the ending of the book that you wrote earlier. You won't find yourself going back to an earlier chapter and changing the look or action of a character due to a major difference in the final chapter. You will already know where you are going, and this will assist you in avoiding major (or even minor) conflicts between sections of the book. You may not spot these conflicts easily, but your readers often will, and an obvious or major discrepancy will probably spoil the entire story for them.
I'm worked on the final chapter of “Mandate” last night, for this very reason....and, now I have the entire rest of the book to write. It was such a powerful and touching ending, IMHO, that I only hope I can do justice to the chapters that will lead up to the final moments of the book.
Good luck on the “destination” of your next book.