Practice makes perfection!!!
(1) Watch some English shows. 'Friends' is a classic one. This will help your listening comprehension.
(2) Try reading out some English newspapers/books loudly everyday. This will assist you in building up your vocabulary and confidence.
(3) Writing is a bit tough though. It depends on the purpose of writing. For business writing, you might want to look at what GOOD business writing is.  Have a look at your boss's emails and try memorising his frequently used phrases. e.g. 'Going forward' , 'plan of attack' etc. etc.
(4) When you can not do the first 3 tasks, try this. If you are on a bus or subway train, you can talk to yourself in English or even think in English. We all do that when we 想心事。Just change the language from Chinese to English. It might be difficult at the start, but it will be a lot easier over time.

GOOD LUCK!

Thanks very much！嘿嘿

Regards！

thanks！

thanks！！！