The promise of a new day
If you have a basement, take off enough doors in your house and lean them up against the basement wall, from a corner to as far down as you want protected space. Put every mattress you have up against the doors. Put anything else large you have up against the mattresses. The more bulk you put between you and radiation, the more protection you will have.
In the room right above the corner of the basement you are making a shelter in, turn bookcases over and throw as much bulk on the floor as you can. Tape plastic to the windows to keep radioactive dust and debris from coming in through cracks.
Put food, blankets, light, water, medicines, whatever you need inside your shelter so you don't need to come out. Don't forget a chemical toilet. If time is too short, you can make a sawdust toilet: 5-6 gallon plastic bucket, a toilet seat, and a lot of sawdust, plus thick garbage bags. Line the bucket with a bag, use it, then throw in sawdust which will absorb much of the odor. Throw the bag out of your shelter when it becomes obnoxious. Remember, you will probably be in the shelter for a while, several weeks is not unthinkable, so bring games, toys, whatever to keep busy.
Block the entryway to your shelter with another door/mattress or whatever you have. You can also use sandbags filled with dirt to make a door too.
Make sure your radio works from your basement or you won't know when it is safe to come out. Have a cell phone with you too. You can get hand-crank rechargers at http://beprepared.com/product.asp_Q_pn_E_CL%20L530_A_name_E_Wavelen....
Print out a copy of the Nuclear War Survival Skills manual at http://www.oism.org/nwss/. (It's probably cheaper to buy one. You get the most current copy and most importantly, the pictures are better quality.) It instructs you how to make your own geiger counter and much, much more, including an expedient fallout shelter that you can dig in the ground (if you don't have a basement).
Other large mass objects you can use to block radiation is dirt, water barrels, columns of tires filled with dirt, bricks, cinder blocks, whatever you have around the house...sofa, refrigerator, washers, dryers, etc.