I figured since this was empty I may as well start off with some stuff on the non retail version. The experience players know all this so its for new players.
Always kill the enemy who is most likely to kill you first. For experienced players this is a no brainer. For new players its not so easy as they assume whatever is closest is going to kill them first.
An example is if you have some chainsaw guys coming towards you and some normal dead guys and a couple screaming girls. The chainsaw guys are the hardest to kill and do the most damage but they're slow which makes them easier to just walk away from. The normal dead guys approach steadily so they arrive first to attack you. The girls on the other hand kinda hang back out of the way. They have a range attack which allows them to stand behind the other dead ppl and scream you to death. Even though they're the ones who are furthest from you, they can deliver the first attack and if they're shielded by the other dead ppl then you can't easily kill them to stop their attack.
The crawlers are the ones who kill me and many experienced players the most in early game. If you don't have vest (armour) when they start attacking you then they can kill you very quickly. Once they're on you, trying to shoot them off you with a shotgun or hunting doesn't work so well as you'll miss most of your shots, it can be frustrating. The best weapons against them when they're on you is dualies (two handguns) or bullop.
The best method though is to kill them at far range with a winchester so they never get close enough to attack.
Near the end of the round when you've killed almost all the dead people, it can be good to leave 1 alive to follow you back to the shop, that way you can kill it outside the shop door and get extra time to refit your weapons. In some maps the shop can be quite far from where you're battling so it becomes more important to keep one alive.
When flesh pounds come (the big guys with the yellow light on their chest that turns red), don't shoot at them unless you have a plan to finish and kill them. They walk at a decent pace, but once you upset them, their chest light turns red and they start to charge and will kill most people in 1 hit (2 if you have armour and luck). The formula to kill a flesh pound is basically 2 hits with a power weapon (or the equivalent damage). 2 grenades, 2 law rockets, 1 grenade + 1 law rocket, 1 law rocket + 1 hunting rifle shot work. You can also shoot them with smaller weapons but it takes a lot longer to kill them and unless you're good at getting away, they'll rush and kill you before you kill them.
If you have a group of 3-5 flesh pounds coming at you together then it becomes tricky because the odds of killing all of them together is very low. In that situation the best bet is to run and try to single one or two out and kill them together or get enough distance between you and them that you can attack the whole group and run away for long enough that they calm down and stop raging. Most maps have pickups and if the map is big enough then you can keep running and finding more ammo/weapons to continue the battle.
These next ones aren't really strategy but more of manners:
In some shops there is limited space so very few people can get in to buy. If you're playing with many people and you're on a map with such a shop, try to get in, buy/reammo and get out quickly so the next person can get a turn. Sometimes people are inconsiderate which leaves part of the team with low or no ammo for the next round which can be death for everyone.
If you don't have any ammo but have an empty hand gun then ask someone if you can borrow their dualie for a moment to reload. When you get the dualie, throw it on the ground once and pick it up again to re-ammo your hand gun then throw the dualie back to the other player. If you have extra weapons and someone doesn't have any then you can throw a weapon at them and if they have room in their inventory for it then they'll auto receive it, else it lands on the ground and you can pick it up again.
If you're new to playing, try not to weld doors inside the buildings/houses that join areas where players are battling, especially if these playing areas are small. The worst thing is when you're in a fight and start backing up to go thru the doorway you just came thru and find that a new player has closed and welded it and left you on the other side for dead. It's safe to weld outside doors which lead to zombie spawn points, just don't weld the inside ones which block off people's safety routes and never weld players out and block their only escape route.
Another thing is don't steal other player's weapons, it can ruin their game. To know if a weapon is someone's or not is easy. If they're standing, crouching or jumping on top of a weapon it means it is theirs, even if they don't seem to be able to pick it up. If they decide they don't want it then they'll leave it and walk away (This doesn't always apply inside the shop though, thats different)
During shop time you'll see people throwing their weapons on the ground in the shop, usually in a corner or to the side. This does not mean they're opening up a free weapon shop for you to come take all their weapons, it means they're reorganizing their inventory and putting their weapons on the ground to do so. If you accidentally pick up someone else's weapon just throw it back . If someone tells you that you took their weapon then give it back.
Always kill the enemy who is most likely to kill you first. For experienced players this is a no brainer. For new players its not so easy as they assume whatever is closest is going to kill them first.
An example is if you have some chainsaw guys coming towards you and some normal dead guys and a couple screaming girls. The chainsaw guys are the hardest to kill and do the most damage but they're slow which makes them easier to just walk away from. The normal dead guys approach steadily so they arrive first to attack you. The girls on the other hand kinda hang back out of the way. They have a range attack which allows them to stand behind the other dead ppl and scream you to death. Even though they're the ones who are furthest from you, they can deliver the first attack and if they're shielded by the other dead ppl then you can't easily kill them to stop their attack.
The crawlers are the ones who kill me and many experienced players the most in early game. If you don't have vest (armour) when they start attacking you then they can kill you very quickly. Once they're on you, trying to shoot them off you with a shotgun or hunting doesn't work so well as you'll miss most of your shots, it can be frustrating. The best weapons against them when they're on you is dualies (two handguns) or bullop.
The best method though is to kill them at far range with a winchester so they never get close enough to attack.
Near the end of the round when you've killed almost all the dead people, it can be good to leave 1 alive to follow you back to the shop, that way you can kill it outside the shop door and get extra time to refit your weapons. In some maps the shop can be quite far from where you're battling so it becomes more important to keep one alive.
When flesh pounds come (the big guys with the yellow light on their chest that turns red), don't shoot at them unless you have a plan to finish and kill them. They walk at a decent pace, but once you upset them, their chest light turns red and they start to charge and will kill most people in 1 hit (2 if you have armour and luck). The formula to kill a flesh pound is basically 2 hits with a power weapon (or the equivalent damage). 2 grenades, 2 law rockets, 1 grenade + 1 law rocket, 1 law rocket + 1 hunting rifle shot work. You can also shoot them with smaller weapons but it takes a lot longer to kill them and unless you're good at getting away, they'll rush and kill you before you kill them.
If you have a group of 3-5 flesh pounds coming at you together then it becomes tricky because the odds of killing all of them together is very low. In that situation the best bet is to run and try to single one or two out and kill them together or get enough distance between you and them that you can attack the whole group and run away for long enough that they calm down and stop raging. Most maps have pickups and if the map is big enough then you can keep running and finding more ammo/weapons to continue the battle.
These next ones aren't really strategy but more of manners:
In some shops there is limited space so very few people can get in to buy. If you're playing with many people and you're on a map with such a shop, try to get in, buy/reammo and get out quickly so the next person can get a turn. Sometimes people are inconsiderate which leaves part of the team with low or no ammo for the next round which can be death for everyone.
If you don't have any ammo but have an empty hand gun then ask someone if you can borrow their dualie for a moment to reload. When you get the dualie, throw it on the ground once and pick it up again to re-ammo your hand gun then throw the dualie back to the other player. If you have extra weapons and someone doesn't have any then you can throw a weapon at them and if they have room in their inventory for it then they'll auto receive it, else it lands on the ground and you can pick it up again.
If you're new to playing, try not to weld doors inside the buildings/houses that join areas where players are battling, especially if these playing areas are small. The worst thing is when you're in a fight and start backing up to go thru the doorway you just came thru and find that a new player has closed and welded it and left you on the other side for dead. It's safe to weld outside doors which lead to zombie spawn points, just don't weld the inside ones which block off people's safety routes and never weld players out and block their only escape route.
Another thing is don't steal other player's weapons, it can ruin their game. To know if a weapon is someone's or not is easy. If they're standing, crouching or jumping on top of a weapon it means it is theirs, even if they don't seem to be able to pick it up. If they decide they don't want it then they'll leave it and walk away (This doesn't always apply inside the shop though, thats different)
During shop time you'll see people throwing their weapons on the ground in the shop, usually in a corner or to the side. This does not mean they're opening up a free weapon shop for you to come take all their weapons, it means they're reorganizing their inventory and putting their weapons on the ground to do so. If you accidentally pick up someone else's weapon just throw it back . If someone tells you that you took their weapon then give it back.