Firstly remember that your eyes are particularly sensitive to radiation, and that your reproductive organs need protection for the sake of any children you may have. Don't eat, drink or breathe in anything that might be radioactive - radiation does far more harm inside your body.
Smoking makes things worse.
There are three basic ways of protecting yourself from external radiation. They involve time, distance and shielding. Stay in the area for the shortest time possible. Keep as far away from radioactive sources as you can. Use long-handled tools to pick them up.