Inspiration can be quite tricky. A good idea can strike you anywhere and if you don't record it, it can be lost forever.
I always have my RPG moleskine notebook in my pocket to write down ideas, and I have found it unvaluable to be able to work for my next game anywhere and anywhen, when I have a few minutes.
I use it not only to record my ideas, but I have begun to use it to prepare my RPG sessions (which means I am going to need it for Showdown and Savage Worlds) and to refer to it during my gaming sessions.
A moleskine notepad doesn't take much space on the table and it can contain all my references for the scenario I am mastering, regroup all the stuff I want to be able to look quickly (an index of what I want to find for the game, sketch maps of places not developped in the scenario, stats and descriptions...).
I have encountered two problems when using a moleskine for this kind of things:
-First, what you write down in the notebook is not necessary grouped logically, so you need a way to reference it.
-Secondly, it can be quite tedious to write again and again empty NPCs character stats blocks to fill them.
The first problem is easily solved by numbering each right page. Then, when you want to refer to somewhere in your moleskine, you just have to note that number and the quadrant where it is located. For exemple, in the moleskine here, refering to the map drawn on it would be 22C.
For recurring stats blocks, I just took the solution from Moleskine itself. On their site, they have made available empty pages that can be glued in a notebook.
So you can add squared pages in a lined moleskine or you can add a storyboard page in a squared notebook,... or any combination.
I just made moleskine stats blocks pages (one for NPCs and one for vehicles), they can be glued in your notebook. I prefer to print them on A4 sticker paper. I cut them and, when I need one, I stick it in the notebook. I write the game stats on that page and any notes I need on the next one.
As moleskine have a pocket inside the back cover, I can carry a few blank stats pages with me.
You can download the Moleskine SW pages (NPCs and Vehicles) in english here and in french, here.
Content is self-explaining, but I added a small silhouette on the right bottom of the page. It is intended to record armor values if needed or sketch anything that can be useful for the GM (the place where a knife is hidden, the parts covered by the armor,... wathever).
Don't forget to print them at 100% by unchecking the "fit to page" button in your printer setting, or it won't be the right size.