To begin with, I don’t look at the book, and just listen to it the audiobook [7] several times, trying to figure out what the content is. Then I read it the book [8] and write down in a notebook the vocabulary that I don’t know on notebook. The next, memborizing I try to memorize the vocabulary words and listen to the audiobook again. Still, I don’t look at the book. Thus, I listen to every audiobook was listened to about twenty times. And one of the most important points is, that I am not completing these twenty times continuously [9] but spread them in over about one and half years. This stratigic strategy [10] keep me from forgetting what I’ve studied. 

The strong desire of being to be good at English drives me learning to learn it everyday. I am looking forward to be having no difficulty of listening, speaking, reading, and writing some day [11]. I am sure the that English would will open a window through to the world for me.

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[7] The pronoun 'it' would refer back to "the book".

[8] The pronoun 'it' would refer back to the audiobook.

[9] The following is more natural:

"I am not listening to the audiobooks daily, but listen to them over a period of about one and a half years."

[10] The word 'strategic' (please notice the spelling) is an adjective:

"My strategic approach to learning English is..."

Above, the noun is 'approach' and its adjective is 'strategic'.

The word 'strategy' is a noun:

"My strategy for learning English is..." 

[11] The following is more natural:

"I am looking forward to the day when I have no difficulty reading, writing, speaking, and listening to English."

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Your strategy is working.  Your English is very good!

Learning English

A few years ago, I began to realize gradually [1] that I have no specialty so far in my life. I learned things eagerly for interest in the past years, such as computer science, listening to classical music, playing badminton, and so on. But they’re just hobbies and have nothing to do with my job. The most important thing is that these hobbies are not essential abilities for me and people around me. People don’t care about what you are interested in. An idea came upon me at this moment. Why not improve my English skills? Because English is an international language, there are many benefits for being good at English. In the first place, you may communicate directly with most foreigners whose native language is different from yours. That make you easier makes it easier for you to be friends with a foreigner, and to know different cultures. In the second place [2], most of the information in the world is written in English. That make you absorb things quicker. In the third place, how could a traveler experence a rich journey without possessing good English skills? The advantages of being good at English are far too numerous to enumerate individully.
Since then, I have been studing English on my own for two and half years. In the beginning I didn’t know how to learn it more efficiently. Afterward [3] I contacted unintensionally [4] a set of audiobooks [5]. It contains a variety of themes such as fairly tales, fiction, proverbs, literary classics, classic movies, culture, society, commerce, art, history and so on. Euclid said that there is no royal road to geometry. It’s the same to with English. I have to learn it step by step, then I could can improve my English. The thing was how to remember the massive content of all these audiobooks. Concluding the opinions on the net [6], my approaches are as follows:

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[1]  The phrase "began to realize" and the word 'gradually' convey the same meaning here, so you only need to use one or the other:

"A few years ago, I began to realize that I have no specialty so far in my life."

"A few years ago, I gradually realized that I have no specialty so far in my life."

[2] This is not really an expression.  We would normally say, "In the first place, ..." and then perhaps, "Also, ..."

[3] The word 'afterward' (or better, 'afterwards') usually means immediately after.  For example:

"We went to dinner in a restaurant.  Afterwards, we went to watch a movie."

If you mean days, weeks, or months later, we simply say 'later'.  For example:

"In the beginning I found it hard to understand spoken English.  Later I discovered audiobooks."

[4] The spelling is 'unintentionally'. However, this word does not work in your sentence.

[5] Discounting the word 'unintentionally', here is your sentence:

"I contacted a set of audiobooks."

The word 'contacted' does not belong here, because we do not 'contact' audiobooks.  Rather, we "listen to" audio books:

"I listened to a set of audiobooks."

[6] I don't really understand this phrase.  Perhaps you mean:

"Taking into account opinions I have found online, ..."