Remembering Clippy[0], I have written a snippet for .vimrc that gives me a random advice (hint / feature / hack) when starting vim. It is not certain that I will need it here and now, but at least I will refresh my memory, and maybe I will be tempted to try it and internalize it during the session.
Many (at least half) of the hints are taken from Drew Neil's wonderful "Practical Vim". Highly recommended!
The hints are written in a terse manner. If you are new to vim, few of them will enlighten you on the spot. But the others might still pique your curiosity. Just explore further using :help... or read "Practical Vim".
The idea is that eventually you will curate `vim_hints.txt` on your own, adapting it to your needs (and your memory).