As an English teacher for many years, I have found that teaching grammar in my classes might help my students to take tests efficiently but not for real English.
Remembering grammar rules may confuse you. You may have a huge goal to be great at English and to speak really fluently but when you start with the grammar learning method I believe you, finally, will drop down. This has been my experience in teaching English for more than 8 years for Thai students.
Focusing on grammar will boost up your boredom and you will be more discouraged than encouraged. This is because there are too much grammar rules to remember in a short time. You may take 3 more months to know them all. However, even you know them all but you may always make a lot of mistakes like I used to.
The question is why grammar is important in using English but not important for learning English. The answer is native speakers always use correct grammar in sentences. Even one native child never says “I go to school yesterday” but he says “I went to school yesterday”. How can he say the correct form of sentence without studying from grammar books like most of us did. According to the research in language learning, they found that studying grammar directly from textbooks or grammar books make less effect than learning from the real English. People who study grammar for 10 years or more may say wrong pattern in their speech. You can change the problems in grammar mistakes into the chance for improvement. I suggest that when you still make a lot of grammar mistakes, you still have a room for improvement. I believe, according to my experiences together with the researches by many linguists, that the best way to learn grammar rules is not to learn directly from textbooks, but the most direct way to learn them by examples. You must see and hear a lot of examples from real English sentences. That is the great way to improve your English ability suddenly without boredom.
In addition, you must stop using grammar books but try to find sources of real English. I do not suggest you to listen to English from cnn.com if you still get trouble in listening to the fast speeches. Besides, you should try to find the sources that you can understand sentences suddenly without translation. By this way, your grammar will improve subconsciously without awareness. You will be able to use English with fun and full of joy. Because you don’t need to be afraid of making grammar mistakes. Though, you may make some mistakes in speaking or writing but it will be corrected later if you listen or read more and more real English. This method is working very well right now. It is the great way to learn English without going abroad. You can stay in Thailand and speak English very well with clear pronunciation. But if you are still trying to learn grammar books, it may be too late for you when your English will be natural and clear for communication.
The goal of all languages in the world is to send messages by understanding the meaning. If you still worry about mistakes, you will never try to use English confidently. This is the way to failure. Try to use English without any fear and remember you must have enough input in English before you can generate output. Wish you all get well and enjoy your English learning by yourselves.