Start with three health. Zombies will try and take your health away, but you can find more health along the journey
You'll find medikits along the way. They will have health and ammo in them. So stay alert and stock up.
Enemies take two bullets to kill. Unless you head shot them. But be careful, some of them are runners.
Everyone gets a hand gun with some ammo, conserve it. You'll find more in medikits, but it's rare.