One of the handiest tools that I have had while modeling and painting miniatures has been a thick little notebook that I am able to carry around with me. I jot down ideas or sketches of things that inspire me or that I want to remember. The single best thing that has come out of this is that I have been writing down my paint 'recipes' whenever I start a new project.
I am a compulsive army collector so I will usually have several projects going at once. Oftentimes months may go before I come back to a project. Before I started keeping a notebook I would forget the steps in my painting scheme and would have to figure it out again. Since I started keeping this written down it has been very easy to go back and pick right up where I left off.
I also make sure to take notes when doing a test model. At one point I had started painting up some Black Templars using a white color scheme. I abandoned that project and moved on to my Imperial Fists.When I started up my Dark Eldar I played around with a red scheme and finally settled on the white pattern that I had originally tried on my Black Templars.
Does anyone else use a notebook or some other way of keeping up with ideas and recipes? Let us know in the comments.