The common kitchen aluminium foil works. We now use it in our lab to shield stuff. A few layers of it works much better than the expensive stuff from 3M.
Since most of the strong RF around us are in the S-band, around 12cm, you could just use a metallic mesh with holes smaller than that (<1cm). I use wire fence on the walls facing the antennas and it reduces the radiation from 2 V/m to around 0.4-0.5 V/m. From my experience, everything below 0.3 V/m, or 0.2 uT on the magnetic side, is fine.
I would also recommend following the scientific research in this field and to gather your own data. Simple variables, such as pulse and blood pressure, are a good start.