If you want to speak good english then you will have to practice it. Without speaking out you can't be proficient about it. For that you can use the following tips:

• See English movies and try to coup up with the pronunciations they made.
• practice with yourself in front of mirror if you hesitate to speak in front of anyone else in the beginning.
• Slowly try to speak English where ever you can so that you can build up your confidence.
• Make your mind free and don't hesitate infront of others.

Now writing English is easier. You have to careful about the grammar and absolutely precise about your vocabulary. To enrich your vocabulary you can go for different sources like Newspapers, online articles, Novels etc. Also you have to practice your writing skills where ever you are possible. The best way according to me is to communicate in social media in English and slowly you will get better in your writings. Also you can use tools like Grammarly in order to be sure about your grammatical errors.

I hope this answer helps. All the very best for your future endeavors!