"Najlepsze mienie - czyste sumienie." --- Your best/priceless property - pure conscience.
"U skąpego zawsze po obiedzie." --- At miser's place it's always past dinner. (I hope that there is a word “miser” in English

)
"Dobry zwyczaj; nie pożyczaj." --- A good habit; Do not borrow.
"Nie szata zdobi człowieka." --- Clothes do not adorn a person. It basically means that it's not important how you look, but what you have in your head, and what kind of person you are.
There's one great saying used very often by elder Polish construction workers: "Po szklanie i na rusztowanie." --- One more glass (of vodka) and on the scaffold we go!
And finally my favorite one often said by my close friend: "Lepiej być zdrowym i bogatym, niż chorym i biednym." --- It's better to be healthy and rich, than ill and poor.
