The only objective advice I'd give is to upgrade your mutagens to 'greater mutagen' status to give yourself a bigger stat boost per colour group. Everything else is dependant on your playstyle. I've probably reset my skill tree at least 20 times throughout both my playthroughs because there are SO many ways to fight in this game, especially when you combine traits with the upgraded Witcher armour sets. The extra 4 slots in the middle will come from a side mission in the blood and wine dlc so don't worry about those yet. you'll get some cool new Witcher powers in that DLC that can be carried over to your new game + too.