My strategy is based on the assumption that what matters for listening comprehension is quantity of exposure to material that is just above one's level (when it's too advanced for you it's just noise). Not sure if you're a subscriber, if so you already know that when you download the entire set of MP3 files, it comes with shortened versions with just the Chinese dialogue. A few weeks ago, I put these on shuffle and listen to a couple dozen Elementary level dialogues per day during my commute. I have noticed improvement in my listening skill. Also, over lunch I carefully study the material for one or two podcasts, as prep for later listening.