You can add to your vocabulary very intricate expressions and words ,yet if you don't know how to combine them into a comprehensible gramatically correct sentence, your speech won't be fluent.Adding vocabularly will enrich your language and make you able to express more in various ways using a diversity of words and expressions ,but it won't make you necessarily fluent. You need to practice a lot building correct sentences with minor grammatical mistakes ,which will be your basis to deliver clear and adequate speech. The vocabulary presents the building blocks for delivering such a speech, if they are not interconnected well through a sound grammatical structure and a correct word order , they will result in a mishmash,that deviates much from the target of achieving fluency in the language. So it is not only the acquistion of more vocabulary or certain vocabularly that will help you be fluent, but essentially the ability to use this vocabulary in the most efficient way.

The more words you know, the more fluent you'll be. In order to extend your English vocabulary you can follow 2 methods. First is the repetition-based method, where you learn English words by writing them several times or saying them repeatedly until you remember them all. If you patiently follow the process, you will see your vocabulary extended very well. Secondly, you also need have to have a notebook with your own note-taking rules. Each time you log onto Italki, note down any new words in the Questions and Answers section. The only problem is whether you want a rich vocabulary or not. Your plan should answer 4 questions. 1.How many words will you learn a week: 5, 10, 15 or more? 2. When will you learn them? Every other morning or anytime you feel like learning? 3. How often will you review what you have learnt: weekly, monthly or before a test ? 4. What areas of English will you focus on? Sports, music, games or sciences? The answers may vary a great deal from one person to another depending on memory, schedules and interest. You can gain a big vocabulary and improve your English by simply by determining what field of words to learn, making a plan of learning, choosing a learning method and regularly practising your plan and method. Daily vocab learning is better than weekly or monthly. Remember your vocab by drawing a small a picture next to it.For example, for the phrase "make up" draw a small coloured picture of a woman's face with lipstick, eye shadow and mascara. "Make up" also means to make friends again after an argument so you need to draw 2 people shaking hands underneath your first picture. Good luck

Let me put it another way. To be able to communicate in simple sentences, one needs a vocabulary of about 3,000 words. If you want to be fluent, it doesn't matter how much grammar you know or how well you can conjugate verbs, you need to know some vocabulary. Of course, grammar is important, also. So many Americans take years of a foreign language and can barely communicate because they spend that time learning grammar from textbooks and not applying it. Learn lots of vocabulary. You won't regret it.

I think you can accomplish a LOT with a small vocabulary if you are creative! As a learner, you will never know all of the words. There will always be words you don't know. So you need to learn how to communicate with the words you already know today. Even if your meaning isn't exact, it's better this way. Over time, your vocabulary will grow. Don't worry about it too much. But it's good to pay attention to useful new words you hear and try to use them. Please don't look up words in a dictionary and try to use them. This will make your English sound weird.

Try to talk as much as you can in the language. Vocabulary comes after that. The "trick" here is to get your mind to let it flow. Good luck!