If you're having trouble with getting the assistant to wake up, and you don't see an improvement after running through the wizard you get when you say "retrain voice model" or "recognize my voice", you should also be able to get the assistant up by long-pressing the middle button in the navbar at the bottom. You additionally shouldn't need to wait for a response after saying "take a note", just dump it all in a single breath.
> when it occurred to me I should remember to put my shoes on
...Are you mocking me? I thought I'd made it pretty clear that I used that tools to help compensate for a memory problem that does, in fact, qualify as a disability. Try "okay Google, remind me at eight pm to reply to $friend about $thing". Or "okay Google, remind me every day at two in the afternoon to make a dentist appointment...".
"OK Google!"
wait 5-10 seconds for the assistant to chime. It might work if I don't wait, but mostly doesn't. Sometimes it doesn't wake up at all.
"take a note"
wait for the assistant to ask what the note is
"Remember to put your shoes on!"
Check whether the note was taken correctly
Also, if I was actually using the phone for something else:
switch back to the app I was using when it occurred to me I should remember to put my shoes on