The mission where you test the Napalm makes me want to throw my controller.

[Namkcor]

I feel like unless I prep a bunch of distractors outside the mission ahead of time, no way in hell am I completing this. I was using the destroyed bridge as a funnel but they don't clump together well without them. Not sure why they provide you with useless ammo at the start when you really need distractors. SMH

[BioFringe]

You can beat any horde using your bike. Kite the zombies toward your bike. Kill as many as possible. Get on your bike and do a loop to the other side. Rinse and repeat.

You can even use your bike like you're a cowboy and the zombies are cattle. Drive in such a manner as to control their movement and group them together.

Remember that the bike is always faster than a zombie. Use that knowledge to your advantage. All you need is your bike and enough bullets.

[oNo_The_Gamer_TTV]

I 2nd BioFringe, but also, always thin the heard. Draw groups of them away from the main heard and take them out. You don't want to get the whole hoard to come down on you when you could pick them off in smaller groups.

[Noquid]

That mission is actually fun. Search the area for explosives, put bombs near explosive barrels, propane tanks, etc. Move the oxygen tanks to similar spots, shoot to trigger. Near the horde location is a building you can also use to deplete most of the horde. Car alarm + molotov, etc. Lots of options.

One tip: the remote bombs seem to get triggered due to freaks stepping on them, place them on walls or other surfaces off the ground. Then you can trigger when you want.