One simple way to improve your English is to read. Just by reading your vocabulary will get bigger. Also be reading your grammar will improve. And the best part is that you do not have to read boring things. Just chose a book, magazine or website you like and read. Stories are as good or better than newspapers or text books.
One useful resource that we have set up is the online journal Eastlit. Eastlit is a monthly online magazine. It has stories and poems from or about East Asia and East Asia. Many of these are written by local people who do not speak English as a first language. Maybe apart from reading you could also submit you own story or poem. Then you would be a published writer, too!