I'm like a dying man in the desert waiting for the Tips and Notes, but until then, here's an awesome chart of case endings made by another user. I have it bookmarked right next to Duolingo itself, since learning this language without it would be like brushing my teeth with sandpaper.
Thank you for this, it will be very useful. I've found the website this was taken from. It's really worth looking at. There is a good explanation of the 7 Polish cases. Plus a lot more useful information and instruction about Polish Grammar, including PDF's of this and present tense Verbs.
My personal favorite: http://aztekium.pl/przypadki.py?lang=en
It usually works for most words, names, and appropriate phrases. It is especially good for when you write messages in Polish and need to find the cases for Białystok, for example xD Białystok has a really weird locative case.