If you are not effected by an initial blast and radiation burst, the most concern would be fallout. You would not want to breath it or ingest it. A thorough wash/rinse with soap and water would be good for removing contamination after moving out of the fallout area. ditch all clothing that is contaminated. it would be hard to tell if you got it all off without a counter.
Some of the same things Homeland recommended for a possible chem attack are appropriate for fallout.
Duct tape and thick, large sheets of plastic/polyethylene, contractor size thick garbage bags, sealed food and water supplies, stay ahead on necessary drug refills, and perhaps a surplus gas mask for each family member.
Additionally, you'll be wise to have iodine pills to help reduce the risk or thyroid cancer. Non-porous rubber gloves are needed and mask inserts if you wear prescription lenses.
If you go out, you'll need to dress in plastic -- basically a DIY radiation suit. Use duct tape to seal all seams, and learn to use your mask properly.
A geiger counter can be purchased online as well to ensure your environment and people coming inside are not contaminated.
I went though NBC training many times. You spend as much time preparing to go out and come back in as you do outside. Limiting outside exposure is important, but you may not be able to live in a plastic-lined room without more supplies.
With a little prep, some everyday supplies, and some training, surviving fallout is very realistic in Hawaii if the winds are cooperating and taking the radiation out to sea.
