You need as much exposure to English as possible. For example, reading in English increases your vocabulary as well as introducing you to new grammatical structures. Most English newspapers have free websites, so why not choose an article every day? Try to guess the meaning of any words you don't know from the context, before checking in an English-English dictionary if necessary. You can also practise your listening by watching the BBC or videos on TED. Try to speak and write as much English as you can.
Of course, you also need specific exam resources and to practise your exam technique by doing past exam papers. You'll want to get feedback on your writing and speaking in particular, and this is where private lessons can really help. In a one-to-one setting, the lessons move at your pace, are tailored towards your needs and all the feedback is directed at you. A good private teacher can also help you hone your listening and reading skills, giving you lots of practice and helpful tips.
I offer a free 30-minute consultation before starting lessons, where you can explain your needs, strengths and weaknesses. This enables me to create a personalised learning plan for you, and I can recommend books, websites and other resources to help you get the IELTS score you need. Please get in touch here if I can help!
exposure - providing someone with the opportunity to experience new ideas, activities etc
tailored - made for a particular need
to hone - to improve a skill or talent