Basic exercises to practice writing in English include writing answers to questions, inserting missing words into a paragraph and correcting word choices in a text. More advanced writing practice includes keeping a journal, writing stories or writing messages to other people. Consistent practice is the most effective way to improve at writing.
Reading helps writers of all levels develop, as it demonstrates how other writers use their vocabularies to put sentences together. The writer should choose books that are suitable for his level of English, so he is able to read without checking a dictionary. If he's just starting to read in English, he can choose a book he has already read, that way he understands the story.
When the writer starts writing in English, he should perform basic exercises to develop his vocabulary and grammar. Once he has a grasp of the language, he can create his own texts. To keep himself interested, he should write what he enjoys reading. For example, if he enjoys news articles, he could write articles. A journal works well because the writer is able to write about his day and make writing a habit.
Exchanging messages with others allows the writer to practice his reading and writing. If he writes to native English speakers, they can help him by giving him advice and correcting his mistakes. Writing partner options include pen pals or online language forums.