Good advice from the website you listed.

There are water proof storage bins that you can get from Amazon or Wal Mart or the likes. You should put important documents in there. My sister's house, after Hurricane Katrina, had 9 feet of water and all her precious pictures were ok in one of those bins.

Like others have said further up, water is a good idea and also you should consider canned foods and a way to open them. Store these as high up as you can.

One more thing you can do is get an ax, in case you are trapped in an attic.

Lastly, when in doubt get out. If you feel like your area is proned to flooding evacuate early. Many nasty critters come out after a flood and they are no fun to battle.