Neighbourhood watch

A handful of teammates is a good thing to have when facing a crowd of zombies, but you don't have your perfect zombie fighting squad by your side at all times.
It would be a good ideas for neighbours (and perhaps coworkers) to be allies, and not competitors, if they find themselves surrounded by the undead together, and unless you are also good friends, this won't happen without planning ahead.
What would you involve your neighbours in when devising your zombie survival plan? (assume that your neighbours all also wants to plan for zombies)

- Mutual rescue:
Of course, you have each other's phone number, but in case the phone stops working, you need a quick and efficient means of warning each other. A siren and beacon to draw attention, then messages posted at the window can do. If you wake up in the morning and a zombie is clawing at your bedroom window, you may want to know whether there are twenty more clawing at the walls before you do anything. That's something best checked at some distance. The neighbour can also be in better position to kill a zombie than you.

- Shelter:
Having to survive for a long period of time on limited supplies would make anybody anxious about sharing them. But if your house burns down, staying at your neighbour's for a few days and sharing his food is probably the only way you can survive at all. Better having previously agreed on the conditions: how many days you have to find a new place before moving out, how many meals, and what you can give in return if you need to stay longer (since you have to scout to find a new house anyway, you can salvage some useful items for him on your way)

- Land and space:
Inhabitants of an appartment building can make sure the whole building is a safe zone. Some backyards are almost sealed up between houses and would only need short lengths to be fenced to be secure. This all requires prior preparation. Either build the fences in advance, or have the maretial at hand. Make sure most of the gardens are used for edibles, plant fruit trees now so they're mature when the apocalypse comes. Same goes for a roof greenhouse on an appartment building: start nagging the landlord now, because you'll need the thing working and your vegetables in any state but "seed" when you can't just go buy food anymore.

- Trading and sharing:
There are some things that you might need in a zombie apocalypse, that won't be missing if you share them, and that you don't need before it. Mostly tools, which last long even if multiple people use them. Make sure the neighbourhood group has one of each important one, then you can move them around. Think about a laundry board: you probably don't want one now, but if there was no more electricity, it would be useful again.
Services as well: better have one doctor and one botanist than two doctors. Make a list of the available people's skills and how they complement each other, and prepare knowing what you'll need to learn and/or compensate for.

- Euthanasia:
You need to know who is willing to finish you off or not. I'm not just talking about shooting you if a zombie bit you, but also if you have a severe enough injury or sickness. If you go out to hunt a sheep that wandered in from a farm nearby and your buddy shoots you in the stomach by accident, you want to know he'll have the guts to finish you off if you ask him, rather than leaving you behind to bleed to death in horrible pain.