There are three things you need to do! Practise, practise and practise. Actually, there is more to it than that and in the same way that not every patient needs the same medicine, different people need different approaches. Some people do not have much experience of writing their own language. Some people do not really enjoy writing. However, if you need to improve your English writing skills, there are some simple things you can do.
To start with, reading is very important if you want to improve your writing. When you read, as well as take information, you can see how we communicate in written English. You can see the vocabulary and the grammar. You can see how the sentences are connected to each other. You can see how we explain ideas in English. Depending on what type of writing you want to do, you can choose the kinds of things you are going to read. If you want to do creative writing like stories, you can read stories to see how writers create them. If you need to be good at writing emails and letters, you can read examples of these to see how it is done in English. If you want to improve your academic writing for an exam like IELTS or for university, you can read academic texts and articles which will help you to understand how good academic English is written.
Reading is extremely important, but it is not enough. That is where ‘practise, practise, practise’ comes in. A very good way to start practising is to keep a diary. If you keep a simple diary recording what you do every day, you will become confident, and it will help your everyday vocabulary and grammar to develop. When you become more confident, as well as writing about what you did every day, you can write about how you feel about your studies and the place where you are living. Writing a diary is a very good way to start building your writing skills as you do not have to think too much about ideas as you know what you have been doing.
If you are studying English in a good language school, some writing will be part of the lessons. You will want to record new vocabulary and grammar that you learn and will probably record it in a notebook. Also, you might do some different types of writing in class, although in a good language school, not too much time will be spent on this because the focus will be on communicating. Some students choose to do lessons, especially for writing skills and in these lessons, the teacher will help you to become a better writer. However, even in a general English class, you can ask your teacher for advice about writing. You can ask them to suggest topics for you to write about and to check your work.
Students who are preparing for exams like IELTS of FCE which involve doing writing attend classes focussing on developing writing skills. The students learn how to brainstorm (get ideas), how to plan their writing, how to write good paragraphs and how to develop their ideas and connect them together in a logical argument. They also learn how to check and edit their writing.
To conclude, improving writing skills is an important and difficult project for students. However, if you prepare by doing a lot of reading, by doing a simple practice like writing a diary and then by getting help with more complex writing tasks, you will become a good writer in English.