I would not stress builds and minmaxing much. Even when I played on Death March, I simply picked what I liked from the description, what seemed most interesting or useful. So I always ended up with a mix of swordsman and sign user, having all the signs unlocked and available and the cool sword skills as well. Alchemy gets some basic use, although if you go into it there are some super strong skills. Make sure to learn dodging well, rolling should be used mostly only when you need to get out quickly.
BTW if you are playing PC version, be sure to check out Immersive Cam and Volumetric Clouds over Skellige mods, they are great. And note that you can also change movement system to be more responsive (alternative, in the menu options) and customize your HUD, Witcher sense fish eye effect etc. I would also recommend disabling point of interest markers on map (in HUD options), game is better when these are discovered naturally instead of knowing about all beforehand.
