Well first you would need to find out what the cause is of the bouncerate.
This can easily be determined through google analytics , by looking at you users flow, demographics and so forth. You may spot a high bounce rate among certain refered traffic , on a certain page or from a certain demographic , once you have determined the cause and place you can only then start working on a solution .
More than most times its one of 3 things , non responsive websites , irrelevant or bad content , site speed.