WALKER: The easiest and most basic of the zombies, kill them however you wish. Just remember not to overuse your stamina, as even the weakest zombie can inflict massive damage and a knockdown when your stamina is drained.
INFECTED: There are several ways to approach infected, the method depends on the encounter type:
All around approach: Treat others as you want to be treated; The Golden Rule.. If you are playing Sam B and have the tackle ability, run at them as they run at you, payback's a b****.
Charging you from the front: Use any weapon with high force, and play baseball. Wait for them to get in range, and strike for the head while standing still. A sledgehammer is the best approach, as you may have to swing early but it almost always one hit kills. Using Sam B's LT+RT attack will knock them down and inflict massive damage (This must be unlocked, it is the last ability in the combat skill tree.)
Flanking from all sides: Dodge to the left or right(I didn't say front or back FOR A REASON)and put a little distance between you and them, and repeatedly kick them to regain stamina and buy some time to fight them. Usually having full stamina will make most kicks a knockdown, giving you time to keep striking them back to the ground and methodically kill them all.
THUG:These guys are a damage sponge, it takes a little time to whittle them down. YOUR DODGE SHOULD NEVER BE FORGOTTEN WHEN FIGHTING A THUG! To dodge, simply press jump while moving in a direction.
METHOD 1: Use a sharp weapon to dismember their arms, making them essentially useless (they will just try to bite you) or use a blunt weapon to break their arms for the same effect.
METHOD 2: Strike, jump back, repeat. If they swing as you're closing in, stop and wait for the swing to finish, and attack before they swing again.
TIP FOR FIGHTINGLARGE CROWDS OF ZOMBIES NEAR A THUG:If you are getting chased by a crowd of zombies and don't have enough stamina to fight them all.. Let a Thug punch you.. It will inflict moderate damage and knock you to the ground.. but the crowd will walk away form you back towards their spawns (buying time) and you will get back up with FULL STAMINA. See? Thugs are very useful in this way.
There is mostly only one appraco to Rams that works consistently: Wait for them to charge at you, and dodge to either side. Then attack to bloody wound on their back. Remember how many strikes you can get before they retaliate, it's better to stop attacking early and wait for the next charge than damage them faster and get knocked down.
NOTE: Fury attacks only do 1 damage if attacking their front side, same as other attacks. Don't waste your time.
Same as infected, stand still as they charge you. When you get close, kick them or use Sam's RT+LT ability. Once they have been stunned once, attack one or two times, and kick them to stun again. Repeat this until they are dead: Slow and steady.
Easier than they look: Just charge right in and start attacking or kicking. They are easily stunned by attacks with moderate force, so often you won't even need to kick them. Just wait for them to use a long range attack and run at them. Tackle itself will stun them, as will most attacks. Just keep hitting them and for safety, try to stay on their backside.
Use the mobs of humans and zombies coming at you to build Rage. Save this until you get to the boss. When he calls for "Protocol 66" a wave of zombies will be released, and the gate to the boss will be smashed open. You can now run up the to helipad through that gate. IF YOU HAVE Sam B's final fury tree ability, just activate fury and start punching him. You may have ot dodge after every 4 or 5 punches when he attempts to charge, but for the most part you will kill him in a single fury activation if you avoid getting knocked down and just keep punching him.