Personally I find the King's boring and hard to stay awake to. They do however cover all the material necessary and then some. I recommend to my students that they use the Jeppesen text book, the Gleim study guide and Rod Muchados instrument handbook. I have found that these 3 in combination work great and have had resulted in successful checkrides for my students.
As far as getting organized, save your money don't buy the fancy lap/chart/board/timer/LED/backlighted/etc. You get my point. Instead get a plain clipboard from your favorite office supply store. Get a clip with the flip over ears. Then, laminate your checklist on the back. Put your en-route chart (folded to your area) on the clip board. Use the other clip to hold your approach plates at the top right. This inexpensive trick really works!
Find a place in the plane to secure and extra pen or two. Also a pad to write down clearances.
Another tip, just remember the frequencies when you are given them, you will lose too much time trying to write them down.
Finally what I tell all my students. 'The instrument rating is the hardest of all, but it is also the most satisfying!' Once you get it you can fly anywhere.
Good Luck and keep us informed as to your progress.