I have collected things that I believed would be good reference for quite some time, these are nearly always digital, and 90% off the time I store/find them on Pinterest.
The kind of things I keep usually fall into several categories,
- images I find Interesting
- Images which show the latest trend or style in design/illustration
- Images I can learn from, such as anatomy, technical images, diagrams or a step by step process
- Anything relevant to a project, I will often make a private board and look at relevant images to see how they approached s similar topic.
The good patr about keeping things on pintrest is its available remotely, as lomng as you have a device and an internet connecion you can view your referecne materials.
The Bad side is that you end up with so much, it is a skill itself just to keep these organised and easy to navigate.