I think one of the hardest things about learning Spanish (or maybe even any language for me) is not the vocabulary or the grammar, but rather the phrases that do not exactly translate into English literally. Example, "Claro que si" & others. I know bookstores sell guidebooks to help with phrases because so many just don't make when translated literally. Have you ever made a "common Spainish phrases" masterpost? Usually they are responses, exclamations, etc. They are always hard for me to learn.