One of the most powerful and effective ways to improve your English is by writing, and getting feedback on which parts of your writing are incorrect. I have found that simply colour coding a student's errors and discussing them together can result in huge improvements extremely rapidly. This is why I have developed this method of colour coding, as it helps me present students with their mistakes BOTH visually and verbally.
I have seen numerous students make rapid progress using this method, and a couple have even achieved a score of 9.0 in their IELTS exam, with several achieving scores at 8.0 or above after several weeks of intensive work.
Even if you aren't taking the IELTS, this method is a great way to improve your overall English skills. Understanding which parts of your sentence structure are incorrect gives you a new perspective, and the ability to instantly ask your tutor face-to-face about your doubts leaves you feeling reassured, ready to speak and write with renewed confidence.