I would suggest keeping an English journal. In this journal maybe write a few sentences or a paragraph about your daily life. On another page write down five to ten words (maybe from a book, magazine, tv show, etc.) that you are unfamiliar with. Then, write the definition in your native language. After doing that, try to make two to three natural sentences with each new word in it. If you read, write, speak and listen - it will help reinforce the word in your memory instead of just memorising it.

Hi, Song. Let's change our focus from memorizing the word to using the word. Frequent usage of the word will enhance your memory for it. Do you need to remember how to brush your tooth? Nope. Why? Cause you brush it everyday. So if you use English everyday, how can you forget them? Keep talking, Song!

Ok ,, great then , you ll be memorizing , and repeating and if you wouldnt be able to take a course , maybe instead you can use some online courses and lessons or listen to music and watch movies in english , all this will help too. Your language is phonetically (means its sounds) way different than english , so it is not strange that you would have some difficulty memorizing and accentuating the words , but it is a matter of time and effort in repeating ,speaking and mermorizing as a result .