Search ” ‘topic goes here’ Application Note” on the web.
Topics can be anything:
e.g. TVS Diode, Ferrite Bead, Reverse Voltage Protection.
Not all notes are well written. Search through and find the good ones.
Great way to keep yourself busy with a mobile while out.
EDIT: 2023/03. This one is really something. How to learn intermediate level diy/hacker/maker abilities: go to hackaday, watch all the embedded youtube videos, ignore everything else. Filter out videos that you think aren’t relevant to your needs. Some stuff is less practical / more specialized.