Semi-Pro Tip
DON'T PANIC
I've learned some tricks of the trade through process of elimination as well as serendipitous moments. The map I used for my experiments was San Zombisco.
Do it nice and slow for the 'heavier' maps. Mr. Zed isn't in a hurry and neither should you.
LEARN TO USE THE SHORTCUTS. duerig put it there for a reason. He also made a Zombiepedia for Jebus' sake.
Esc = Menu (also pauses the game)
Space Bar = Pauses and Continues the countdown
D = Depot
S = Sniper
A = Sniper fires into the air to attract zeds
F = Orders sniper to cease fire or fire at will
W = Workshop
B = Barricade
Del = Retreat
V = Displays all the snipers's range and Field of Fire (FoF)
Standing zeds will only attack when you make noise.
'Leftover' zeds from a wave happen only if there isn't a target within (audio) range.
Sniper posts should have overlapping FOF to cover each other. If their range is far enough, you won't have to bother with barricades.
Abandon Workshops if there is an overrun threat and there is no sniper cover. You can always go back to it when it's safer.
To avoid the survivors bunching up in one depot, increase the Survivor Quota (SQ) on surrounding depots to spread them out.
Find as many survivors as you can. The more people on a nest (11), the better (1 sniper 10 spotters). Always MAX out the SQ on the sniper posts - less rounds wasted means more in the skulls of the zeds who want to ruin you day.
Try to lure the zeds in buildings out BEFORE the timer hits zero. Unless you have a sniper battery of at least 6 and 30-plank strong barricades, you will not survive multiple 'Red' buildings and a wave.
Save your game after every wave you've survived successfully. It's there for a reason
NEVER destroy your facilities when you advance. You will need a good fallback line when shit hits the fan up front. This is from painful personal experience.
IF you follow these, the issues of supply lines and survivors congregating in one depot will be minimal.
NOTE:
If however you feel cocky enough, play it with the sudden death mentality. Don't save your game.Destroy and scavenge your rear lines and put all you've got on the front lines. If they break through, that's the end of it.
You can always go back to your most recent save... Pussy.
TL; DR? Then stop whining.