As everyone sais, the only thing which you can do better that the chap next door is to plan in advance.

Buy those extra goods if you can afford the cost and have the storage space. But above all PLAN. Designing a plan, or several plans, will cost you nothing. Its something which you can do at home, during your lunch break, or when you're out and about.

You need to think about the possible scenarios and then sort them into the most and least likely.
You need to be realistic about the duration and extent of any “outage” caused by each event. Is it a 24 hour storm or TEOTWAWKI ?

Simply having a shopping list so that you know your priorities of what to purchase (you don’t want to forget something)
Have a list of the things which need to be done around the house (securing outdoor furniture etc)

Of course buying critical items in advance makes sense, because then you are not competing with last minute panic buyers. You can break up your purchases into things which you can buy well in advance (often one off items like a that spare shovel), things which you can buy seasonally (eg restock long like food stuffs like rice or pasta at the start of the season, and eat them at the end of the season). Of course the more that is done in advance the better, but we all have constraints in time, money and storage space, so you need to strike a sensible balance.

There will always be last minute items, so having a clear list of what to do when the scenario starts to unfold makes sense too. When that emergency starts, at the first signs, you may still want to get to the shops for fuel or to get some items that you are low on, but at least you have a plan and you know what things you want and you have planned on acting on the list at an early point.

Don’t forget to include skills in your long term plans. Its great to have all that food, water and shelter stockpiled in a bunker, but skills can be overlooked when it comes to preparations. For instance a first aid course can literally be a lifesaver. Do you know how to change a tyre ? Can you make emergency repairs to your own home ? Car ? Can you light a fire ? in the wet ? Change a fuse ? Use a signal mirror ? What are your bushcraft / survival skills like ?
Now answer each of these questions for each member of your family !

Planning and following through on your preparations …

… that is what makes you different from everyone else.