Easy way to beat walkers
An easy way to beat walkers is to have a machinegun and flamethrower
A big Boom
On the second level when you get out of the helicopter for the second time. You will find a man in the building. heal him and tell him to follow you.after you get him away from the place he was you will see two canisters shoot them two times. after they explode use your fire extinguisher to put out the fire. In this room you will find ammo and a flame canister with one reload.
Simple Strategy 1
Always keep your team members well stocked with arms and ammo, even if they are infected. It is easier to kill an infected member and take all his stuff then it is to backtrack trying to find more ammo. Don't waste your medkits that determine DNA. If a team member is infected it will manifest itself in due time. Infact it seems to be scripted. I did a test on a member and it showed nothing. Then 5 minutes later he was a nightmare.
1st boss strategy
Under the warehouse through a door is your first real boss. As soon as the cut scene has ended keep yourself to the left of the room keeping your back against the door. There is a tentacle that pops out of the wall on the right. Shot gun the hell out of the boss then use the flame-thrower on it until it collapses on the floor.
You will have to shoot the little spider things as your killing the boss because there is a hatching bubble just the other side of the boxes your standing next to on the left of the room.When you enter the door and the second boss is there there will be a junction box to the right of you. Don't bother with it because it is a waste of time. Go up to the boxes to the left of the junction box and slowly move to the side of them. When you have a good aim at him and he cannot hit you shoot him until when you lock onto him the crosshair is red. Then run up to him and flamethrower him and run behind the boxes. Go up and flame thrower him some more. This might take a couple trys but eventually you will beat it.
Get Witley on your team
To get Witley on your team when you reach the dome at the very start where you see Witley before you take a step throw a blue grenade outside into the snow then the cutscene will appear and Witley will be standing there instead of running. Take your bloodtest and use it on him. Give him a weapon and you now have Witley on your team.
Easy way to beat spiders
If you and your team are up against an army of spiders what you do is-move you and your team into a room with a door control and shut the door, while your in there reload your gun and heal yourself then open the door and kill as many monsters as you can, if there are to many or you are running low on health or ammo close the door again and repeat the process.P.S-dont forget about your team-there no good without amo or a gun