Read as much as you can in English. The more exposure you have to the written word in English, the more you will remember how to spell difficult words and form complex sentences. Pay attention to the variety of ways you can express the same idea to build your vocabulary as you read. Also notice the structure of different sentences. Note how ideas move smoothly from one to another with the use of transitions and how essays use logic and evidence to support their main ideas.
Write down new words that you come across as you read. Read a variety of materials, such as online news stories, magazine articles, children's books, textbooks and instruction manuals to build your general vocabulary more quickly. Different types of writing use words specific to the audience that usually reads them. For example, instruction manuals may use words such as "Do," "Do not," "Avoid," "Use" and other verbs used to command action.
Write as much as you can in English as well. Write a letter or email to an English-speaking friend who can help you correct your grammar and spelling. The friend also can help you learn to use correct sentence mechanics and punctuation to make your writing clearer. If you attend English classes or have an English tutor, ask your teacher or tutor to correct a piece writing you have done outside of your regular classwork. Rewrite your work after it is corrected, paying close attention to the items the teacher corrected in it.
Watch ESL lesson videos online on sites such as ESL Videos and English Media Lab (see Resources). These sites offer lessons in grammar and spelling, as well as cultural notes on slang and other new vocabulary you may hear. The a4ESL.com website offers online grammar quizzes to help you improve your ability to write correct sentences in English as well (see Resources).
Also listen to audio transcripts of news stories on the Voice of America Special English and BBC Learning English websites (see Resources). Write down the words in the story as you hear them, pausing and rewinding the story as necessary. Then check the written transcript of the story to see how much you heard correctly and how well you spelled the words in the story. Write words that you misspelled down in a list to practice.