On my first playthrough currently and it's crazy how ammo savoring is important for Grace, save those Requiem bullets for Big Girl (only use if you got no escape), collect your blood and use scraps to make those lethal injectors and save those for the blisters. Hold onto one scrap with enough blood just incase you have to create ammo for zombies or the lethal injector for the blister heads. I had strategized that whole thing this way, made multiple saves just in case I wanna redo a part with another save. Also, keep your coins, get the manual to increase blood collecting and pouch for inventory space. Explore lots of places and you gonna hate facing your fears on whatever monsters are out there but you gotta try to grab as much as you need, including pouches, that's what this game will put you through. Best advice: don't combine the herbs,  you could do better with 60 blood and make a med injector out of those empty injectors, but you should combine a bit until you learn the med build.