95% of the problems for foreigners in Chinese are going to be vocabulary discrimination, not grammar. That’s for comprehension, anyway. If you really KNOW a bunch of words, you will have amazingly few problems comprehending. For production, I think that faulty pronunciation (segments and/or tones) is usually more the cause of miscommunications or “huh” on the part of the listener than any grammar problems on your part.
I do not teach grammar in any of the languages I teach (English, Spanish, Chinese). My students have outscored other students at the same “level” on grammar-based exams. How? They have heard the correct forms over and over and over again, so that they have acquired the patterns and even the verb forms (in the case of English and, even more so, Spanish). This doesn’t happen just by hearing the language on the street – they are exposed to it systematically, over and over, with vocabulary they KNOW and KNOW WELL. It’s great to listen but you have to know what the heck you’re listening to for it to help you in acquiring a language.
Of course you have to let go of some of the teacher controlled, grammar-freak attitudes to do this. My Spanish students, for example, couldn’t necessarily tell you whether you should use “preterite tense” or “imperfect tense” in one particular fill-in-the-blank exercise, but they could pick the correct form, and they could use the correct form in their own speech and writing. In the end we don’t take tests when we use a language, we get out and speak and listen or read and write it. (Let’s not get into writing Chinese, that’s another thing entirely.)
The other extreme is for the really analytical type, or the person who has a high tolerance for repetition. Get John DeFrancis’ Chinese textbook series and the tapes and just plug into it. (Inspiring titles: “Beginning Chinese”, “Intermediate Chinese”, etc.) Comes in two flavors: characters and Pinyin. It’s straight audiolingualism from the 1960s, but what he does is give you pattern sentences and just plug them over and over again. I was taught Chinese this way in the early 1980s and I don’t remember ever having problems or doubts about “grammar”. (I would prefer to have been taught the way I now teach, as I would have better tones along with the grammar, but you can’t have everything – where would you keep it?)