Ways to remember how to spell physiognomy and disconsolate?

Break it apart to familiar concepts.
Disconsolate -> Dis (not) + consolation.
Physiognomy -> Greek roots which have a particular (phonetically unexpected) manner of spelling and sound, from physio / physical (nature) + gnomon / gno (knowing, judgement).

Perhaps the gno part is less familiar - if you know the words agnostic, diagnosis / prognosis, that's the same roots. "My" is a somewhat popular suffix - monogamy, bigamy.