Classification
Observing zombie should be key; before fighting or attempting to get past a group or horde of them. No matter the kind of zombie they are always found grouped together or in a horde. Never approach a horde unless camouflaged or you know you can plow through it with a hardy vehicle.
Observe whether or not your zombies are attracted to loud sounds. Throw an object far away from your position, if all zombies in that area move to where you threw the object that is something to exploit when there is a group blocking you from your destination. This is a common feature of a zombie so this could be good or bad depending on your party.
Runners or walkers, whether or not a zombie can run or just stumbles is key. People who have played Left 4 Dead know that a horde of runner impossible to overcome unless you immune to the zombie virus. But if it's like in resident evil and runners "red heads" are a rarity then your run in's with them can be cut down to a minimum. If you do run into a runner do not run, kill it, zombie never tire out but you do. In this situation it is best to use guns and keep your distance.
Special Type Zombies the games Resident evil and Left 4 Dead are where you can mainly find special types. These zombie are made through mutations or experiments. Below I will put examples of special types that I believe can most like be created.
Examples of special would be the red heads mentioned before as long as all the zombie are not runners these would be considered special types.
Boomers (L4D) are obese zombie who throws up fluid that attracts zombie; boomer bile is a good scavenger item. Do Not get covered in boomer bile all zombie within that area will attack you unless you can get to high ground or your teammates are there to defend you, your screwed. So America and some island countries would be screwed since boomers could become common. The one upside is you can use boomer bile as a trade item.
CAUTION: Boomers sometimes explode; keep your distance, gunner weapons highly suggested.
Screamers (L4D) this zombie is pretty much like a siren. It screams will attract zombie within that are to you location. Find it and kill it as soon as possible. Mostly likely rare unless your somewhere that being loud is a necessity then screamers may become common mutations.
Tanks (L4D & RE) they are presented differently but are all pretty much the same. They're the types of zombie where you will empty numerous amounts of gun clips in order to kill them. Melee is never recommended with tanks might as well throw cotton balls at them. Keep your distance because they pack a punch and will either knock you down or instantly kill you. This should be a rarity but depending on location may be a common mutation.
Thanks you creators of Left 4 dead and resident evil for making such great games.