The Oxide and Friends podcast [1] did a whole episode on this: Coder's Block (25 Oct 2021) [2].

It had some good stuff in it, the best of which (for me) was: when stuck, write debugging infrastructure.

[1] https://oxide-and-friends.transistor.fm

[2] https://oxide-and-friends.transistor.fm/episodes/coders-bloc...

Edit: punctuation