No matter how many Influence points you have, how you organized your home and trained your hero, your character is always the exposed to death. Therefore, you must always carry some medicine, a cup of coffee (or something else to renew stamina), melee weapon (and one backup) and some optional extras in the form of firearms and ammo, bombs, or even firecrackers to distract the zombies.
Zombies are not very smart, but in this game they are fast, and extremely sensitive to sound. Regular running or even searching some shelves can alert nearby horde. All the time you have to be alerted, even the smallest sound can lure a zombie, and the sounds of fighting will lure next ones.
Sounds can, however, be used to fool the "zombies", drop them firecrackers or set the alarm clock to concentrate them in one place. So a group gathered can easily be eliminated with a grenade.
Cars play an important role in surviving, if you're in the car, you are much safer and more dangerous. When you fight with a horde of zombies while on foot, you have a rather small chance of survival, in the car, however, you are deadly. Therefore, when you are dealing with a infestation or horde, use your car horn several times so zombies hiding in a building will come out straight under the car.
Remember that cars are not indestructible, fast Dodge is easily damaged after a driving through several hordes ... or a tree, slow pickups are more resistant, but harder to control. The best car in the game, forming a combination of strength and speed is police car.
In addition to regular zombies you will have to deal also with more serious enemies, marked on the map with larger red dots:
Feral Zombie, yellow, strong and very agile opponent can knock you in the blink of an eye and hold on the ground. Such an attack can be fatal, especially when lying on the ground while other zombies can attack you.
Screamer is not dangerous zombie, it have no arms, it won't attack you. His weapon is a cry that stuns form for a short distance, and most importantly alarms nearby zombies. Try to eliminate screamers in the first place, preferably from a safe distance with a headshot.
Bloater have a very unusual appearance, thin limbs and gat belly, it's not too dangerous opponent, but if you kill it, it'll generate "smoke" that hurts you and consumes stamina. This type of enemy is especially dangerous if you are in a car, because the stench of the Bloater stays is in the vehicle.
SWAT Zombie, the armed zombies are pretty strong opponents, especially difficult to kill because of the armor they wear.
Big Bastard (Big Un) is the most dangerous of enemies in the game. It will charge you, can tear you apart, it is very difficult to kill, car does a little damage to him and even shots in the head won't kill it quickly. Try to avoid Big Bastards at all costs, and if you need to kill one, try to arrange it so that you will be on a mission with the other survivors to use them as a meat shield.. If you can shoot at Big Bastard's head few times, and when it'll get close hide in a house where he won't be able to enter, and continue shooting.