I dunno, I only did a minimum of sidequests and the game was still pretty difficult to me, I had to do a lot of grinding at places where few sidequests were available. Getting a handle of the combat system is also an essential part. I will say that you'll wanna stick in the level range of the enemies you encounter, if enemies are too easy for you, the game tells you by highlighting their nametags blue, and if they're kinda tough, yellow, and if super tough, red. I'd recommend, instead of doing all the sidequests in an area upon entering it, return to it later and complete them at your leisure, as although they won't reward you much experience by then, you'll still get some neat stuff.