How do I do these courses properly?
I usually work with a notepad at my side, and natural I've been using it for these lessons. But I've gotten this conflicting feeling that I'm suppose to be doing this from memory rather then looking up the answer whenever I'm stumped.
Am I wrong?
^ this. Everyone works differently, and that's okay.
If you're relying too heavily on the notepad, you might give Duolingo a false impression of your abilities, but honestly, at the end of the day, you have to learn according to your strengths, not someone else's. If it's helping you actually learn the language (not just get through the tree), then it's fine. There's no one right way to do it.
I'm also using a notepad; I think writing the words down helps a lot. After I discovered the memrise course another user has prepared (https://www.duolingo.com/comment/16057962) I now review all the vocabulary before I will progress with duolingo; meanwhile I'm doing reviews and look up different grammar ressources ...
I also write down words, especially because the ortographic rules are very difficult for me - I'm a total beginner and my mother tongue is Italian which is completely different from Polish! Besides, it helps me memorize them better. Perhaps I'll be able to rely on my memory later on in the course... I'm over 40 so it's not so effective as it used to be during my school years! :)