I'm not a native, started learning English when I was 20, now 29 and can speak English well and above all have achived a good level of proficiency in the English. Here are some food for thought (something to think of) if you are interesed in it.
-Get a very clear understanding of four present tenses of English, and then go ahead with learning all basic 12 tenses.
-Study model verbs well, understand usages
-Buy a good learner dictionary.(eg. Oxford Intermediate Learners Dictionary"
-When you are learnig a word, always study the words that go together.
eg When you learn the word "mistake" remember that you have to use the word "make"
eg; I made a stupid mistake when I was dong the exam.
In other words, understand the concept of "collocations" well. You will never go wrong.
-Study passive structures, Conditional sentences
-Keep a book to take down whenever you find a new word
-Try to speak in English, never mind making mistakes, the point to remember is that "don't we make mistakes when we speak in our mother tonuge?, do we bother about making mistakes? hardly, right?
-PRACTICE, PRACTICE, PRACTICE whenever you find new words & expresions.
This way your mouth will get familiar with pronuncing English words.
-Learn how we can use language socially in making requests, suggestions, inviting people, advising people. This is where your knowlege on modal verbs comes in hady.
Take the bull by the horns. YOU CAN DO IT.