In the few games I've played I used the blank tokens without actually writing anything on them to represent the unique assets that came up in that game. It was easy enough to remember what they represented and we could jot down the details on a scrap piece of paper.
This is what I did as well. I'm always fearful of using blank tokens, worried I'll run out. So I never end up using any of them! Which kind of defeats the purpose of having them I suppose
There is one I'm considering writing on, as I think it's safe to assume it'll come up often enough. But it's also not really needed as a marker. *shrug*