Damn, it really isn't easy to memorise all these forms of a Romanian noun. I miss some exercises where one would have to write down all four forms of a noun. In my opinion it would make it way easier to compare and memorise them.
I find charts helpful for learning language too, so I make some for myself as I go through the lessons. Whenever I come across a new form of a word, I add it in to the chart. It's helped me remember things better, and I can read through and review them if I need to.