Fenixgoon
Lifer
Loot everything, plants, items etc, you are going to need the coin and materials to get the best potions. Sell items to the corresponding vendor for most coin, weapons to blacksmiths, armors to armorers.
I wouldn't worry about alchemy early on, once you start making decoctions the skill that increases toxicity per recipe known is a godsend. Stacking two decoctions and using healing potions can make for interesting combinations.
If you are having trouble with general difficulty, don't hesitate in putting points into quen(shield skil).
healing quen is OP 😀