1. Do practice IELTS essays and email them to your teacher, or have a friend correct it for you. This website: http://ieltsliz.com/100-ielts-essay-questions/ has many practice ESSAY questions.
2. CAE Writing Corner has tips and practice writing tests / topics for the Writing Paper.
3. ESL Lounge advanced writing has several past tests to practice with.
4. Smart Words: Useful linking and transition words categorized by function.
1. Correct your writing when your teacher or your tutor gives drafts back to you.
2. Choose a part of your returned writing and write it again with all the corrections so that it is perfect. This will help you to remember your mistakes and not make them next time.
3. Write a short paragraph on a topic that you are interested in and give it to a friend or your teacher to correct.