This article is about a vital tool that can help anybody improve their miniature painting, but that I think gets too little attention in painting tutorials or blogs:
Towards the end of 2010 I started to keep records about my painting. Each time I put together a new paint scheme, I write detailed notes about what paints and techniques I used to achieve the results. I also try to keep track of the techniques I used and how they applied to a particular model.
I like to keep track of the paints used to create a certain shading gradient or the formula I can use to reproduce a particular shade reliably and quickly, over and over. In those cases when I do need to mix up a new formula to substitute for a paint that is no longer available, I write it down so I don't have to work out a new match later.
Keeping good records can also help to decide on improvements. If you achieve a great effect by accident on one model - write it down! Even if it's not the look you want for your current project, uou can refer back to it later and try to repeat it some place where it will look great.
Now, it is true that an actual book is not necessary. You could do all of this digitally and keep perfectly legible records on your computer, mobile device or cloud storage. If that works best for you, by all means, go for it. I find that I work best scratching notes onto a physical page, but I may just be old fashioned.