I'm learning English now. In order to improve my writing skills, I am answering questions on the Quora. So if you find some mistakes in my sentences, please tell me, then I will fix them and be very grateful to you, thanks.

My most powerful tip is "Knowledge and action should go hand in hand". it comes from a famous Chinese whose name is Yangming Wang in Ming Dynasty. You could get more information about him on this wiki page: https://en.wikipedia.org/wiki/Wang_Yangming
This tip has two parts. First, you should know something, something about who you are(This means what level do you match), what you want, and how to achieve it. If you even don't know these, you will lose your direction. You will not have the sense to improve yourself.
When you have done enough thinking and get enough knowledge, the next important thing is action. Things won't be done by themselves unless you are involved.
There is a case about myself. I decided to learn English last year, then I accumulated many methods from the Internet. I also viewed many cases from other people who wanted to learn English like me. I knew that I already had enough knowledge about how to learn English. But until February, I didn't get any improvement in my English, because I didn't take action.
From February, I began to recite English words to improve my vocabulary. I learned about 100 words every day(Actually most of them were forgotten soon), it was really arduous. I use "Test your vocab"(http://testyourvocab.com/) to test the result. On February 28, my vocabulary was 2260, but on June 11, it had grown to 5030!

I can read some simple articles now, my English is apparently improved during these days, and it feels so great! Though my English is still very poor, I believe it will be stronger and stronger if I keep learning.

So knowing is not enough, action is an integral part of success. you must spend time on it.