To me, the key to speaking spanish fluently is to be able to understand which tenses to use and when to use them. During my days of learning spanish, it was critical to take the irregular verb tenses and drill them into my subconscious so that there wasn't a large thinking process taking place in order to try and speak spanish. The hardest thing to do is to try and translate from your native language into a foreign language on the fly. It will always sound weird and fractured. These (over 400!) flash cards do just that, and allow you to keep them in your pocket to run through whenever you hvae a spare moment. Buena suerte.