Yay. I feel your pain.
I found that getting a table of the cases: Nom, Gen, Dat, Acc etc and sort of repeating them like a mantra works good, choose like 'der, die, das, die' - nom, 'den, die, das, die' - acc ( I think!) and then your set for endings.
Then the hard stuff is trying to remember which case to use for what! Usually prepostions need the dative - auf der linken Seite etc..., genitive is for possession - Ingrid ist die Freundin meines Vaters. Usually that is effective to remember...
Main thing is just practice, and getting used to it!! I've only had the recent epiphany too
Anything else specific that is just argh?