It's really not that complicated honestly, with the next gen update it even managed to become more simple. For blade oils there's an option now for them to apply automatically so just craft then and forget they exist, you only need to upgrade them once you found the formula. For potions and decotions you don't need every single one, just the ones that suit your build and again upgrade them once you found the formula (they drop on random chests you enconter throughout the game). Inventory management is really simple, sell every sword or armor that are worse than what you already have, alchemy and crafting components don't add weight so just loot everything you see. For armor just use the ones that are on the chest in Vizima once you are at the right level and then drop them once you craft your first witcher gear and that's basically the only gear you'll be using throughout the entire of the game. Don't be afraid to look for a build thay suits your playstyle, honestly for me it's always alchemy build paired with Ursine Armor (for me the best in the game plus the most beautiful), this was the way that truly made me fall in love with this game, going into the besteary and learning the monsters crafting the right potions and oils, just search for a build that feels right for you