Student or Learner
By practising hard, we can improve more and more /.better and better our skill in badminton.
1. Is the sentence natural?
2. I believe it should be 'more and more', but is 'better and better' acceptable?
You would "improve more and more" or "get better and better". That's because "to I
improve" means " to get better" so you wouldn't put "better" after it.