Why study sentences? Memorizing the meaning of individual words... is pretty much pointless. If you want actual fluency, you need to see a word in as many example sentences as possible. That makes the language start to flow in your head. That shows you how to use the word. How it is combined with the other words.

We think that effort always converts into fluency. This is not true. If you memorize the meaning of individual words you won't get fluent and you will spend a ton of effort. But studying sentences is the real deal. Is the method of learning that actually converts effort to fluency. Get some basic grammar, some basic vocabulary, then just dive into sentences and more sentences until you're fluent.