From my experience, I've found bomb scrolls out in the wild and had to purchase enhanced versions from alchemists and herbalist. The same applies for blade oils and potions. Explore the question marks around the map because they are ones that has chests that contain such scrolls for alchemy and witcher equipment. Trust me on this - search EVERY box, barrel, basket, and chest that you come across. Tucked away with the common items you'll find some rare things. Don't pick up beers or food items. You can heal yourself quickly through meditation or potions that are regenerated when you meditate.
As for managing your inventory, if you have access to Novigrad, try to start the quest that locates
. You'll find a merchant inside who sells a saddle pack for 900 coin that will increase your inventory capacity to 160 lbs. Hides and skins usually weigh the most out your inventory, so sell the them at taverns or break them down for parts used when crafting new armor.
DO NOT sell alchemy components because some are very hard to come by and you'll use them to craft potions, oils. Witcher armors and swords are the best in the game, so feel free to sell the other swords, and armor that you across for a decent amount of coin.
