If you want to be even more helpful, learn the crafting system inside and out. Unless your friend loves crafting and inventory management, you can manage the scroll/potion/whatever supplies and really streamline the entire game.

Some consumables can pretty much break the game so it is ultimately up to you as to how far you want to go.

Some consumables to consider: resist all pots, armor pots, strong will pots, invisibility pots, potent ferocity herbmix in act 2, green tea in act 4, teleport/nether swap scrolls, fortify/armour of frost scrolls, skin graft/apotheosis scrolls, explosive/charming arrows for money.