Firstly you should do your homework regularly. Secondly you spend some time in practice section and try to gain as many coin as you can. Third one is you attempt word-meaning related question that is provided by daily basis. And fourth thing you may do is that open lesson one-by-one by giving coins and complete it, because the rank is decided on the basis of how many coins you won yet not that how many coins you have.So that's the way you enhance your rank unstoppably.Thanks