If you think you're not getting platinium fast enough from clearing low danger level dungeons>opening bejeweled chest in high danger ones, and town missions due to your fame being low, you can start to worship Yacatect of Wealth.
Sacrifice every rings/amulet you get from grinding dungeons (and you'll get a lot of them) until you obtain the Goose ally from her.
Each new days, give the Goose a "dish of something" to eat (don't give it a corpse) or cook (you need the cooking skill and an item to cook, you can find many portable cooking device in dungeons) a corpse to be a "dish of whatever corpse" and give it to the servant .
This quality of food (that's what i didn't knew, as i thought the Goose servant ability was buggy while in fact it's all about the food that must be cooked into a dish) will do something very good : the goose once finishing eating it will create a platinium coin.
With this method you can get 1 platinium by day.
Additionally, continue to sacrifice rings/amulets until you get Yacatect 2nd gift : an item that when used once by month will give you 10 platinium coins.
No need to sacrifice rings/amulet for the last gift (a throwable weapon) if you don't need it , you can now go worship your prefered god instead, after a period of anger that you can just wait through, you'll be able to continue using the Goose and the item Yacatect gave you despite worshipping someone else.