Read
Read articles of newspapers, posts of valid web sites or books.
When you read these, your mind have opportunity to memorize the correct style of sentences. Try to read them aloud.
Listen
Listen to news or podcasts that are based on formal texts. Your mind stores what it hears.
Write
write your texts and try to check the correct form of grammar. When you try to write you can find the tips of grammar you do not know carefully.
Speak
Choose a subject. Speak to yourself and record your voice. try to find your mistakes and the correction of them. Repeat your speaking, record and check. Finally you can speak in that subject without verbal and grammatical errors.
