Boy a lot I don't remember. If you got it with all the DLC then do the Turn and Face the Strange quest from the Blood & Wine DLC as early as possible. It unlocks a skill tree that offers the best powers for Geralt. Other than that, I would just suggest you figure out what kind of Geralt you want and outside of main quests then do the quests to get the guy that is best for your build.
So for example if you are going to a glass cannon damage dealer then you want to do the quests that net you the best light armor in the game. If you going to be a tank then go do the quests that get you the heavy armor. That is of course if you playing on higher difficulties. If you just playing casual and want to just enjoy the story then nothing to really worry about as it is a great story.
Our Witcher 3 best builds guide will walk you through four of the very best builds it is possible to create, and what makes each one so powerful.
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The Witcher 3 at IGN: walkthroughs, items, maps, video tips, and strategies
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A build guide and a walkthrough guide if you ever get stuck or need some ideas on how to build Geralt.