Good advice. As someone for whom this is currently relevant, let me add "find a support group".

At least, if it's a common cancer, a group will gather accumulated wisdom and can research better than a single person.

Also, they can help more with practical questions, like financial aid, how to manage sleep and pain, etc.

This is a good addition, although I have not joined one which is probably why I didn't include it in the list. I should find a group to join.