Zombies eat brains, and perhaps flesh depending on the film/book/game/etc.

Zombies do not eat turrets, tesla towers, etc.

The zombies will head in a straight line for you, all the time. They will only attack structures if the structure is between you and the zombie. Once they start attacking a structure, they keep going until it is destroyed. If there is something else nearby, they'll move to that.

The mall map has a large room at the top of the map, lower floor. It has a choke point entrance. Do not construct a centrally placed, well defended 'base'. Instead, place a horizontal wall of sentry turrets along the side of the room. Once you have the cash, put tesla towers beside/behind turrets.

The zombies will always run toward you. So long as you stay reasonably central in the room, they will not attack any turrets. They will head toward you in a direct line, ignoring defences. You will may need to reload turrets - be careful not to draw zombies near. The terrible photo shows a base design in the mall.

Save for the giant **** off tesla tower, whatever it is called. Huge range, massive damage.

Later levels a grid of hesco barriers are useful to stall boss zombies for a while. While they are engaged you should focus on clearing out normal zombies as you can easily kite bosses.

This really doesnt need to be a second tip, but Steam seems to want me to make two sectoins.

Use the auto shotgun. Upgrade it to max by level 40, preferably earlier. Without it the boss fights take forever.

At level 40 (on medium) you get four bosses. Save Lord Souplex for last last. He splits into smaller versions of himself - they are the only boss that will catch you. So take down everything else first - just run backward and fire. It wont take too long with the auto shotgun.

Before you start Lord Souplex reload your turrets. When he splits, turrets are helpful killing the smaller versions.