If you use WiFi in your house, it isn't practical to reduce the exposure without making the WiFi stop working. Instead, there is another solution that requires only small numbers of wires and no DIY or inconvenience to set, using dLAN/Homeplug systems such as the ZyXEL PLA5205 from eBuyer. Be careful to choose a dLAN solution that doesn't come with integrated WiFi.
If your exposure to WiFi is coming from a neighbour's house or flat, you can shield your adjoining walls with paint, or you can see if you can persuade them to either turn it off at night times or implement a dLAN solution such as the one proposed in the first paragraph.
Tablets and wireless game consoles also generate exposure (tablets connect normally through WiFi), so make sure these are turned off completely whenever they are not being used. For reducing your electrical field exposure from a laptop when in use, you may also want to consider one of our earthed laptop trays or laptop earthing leads. It may be worth considering limiting the time anyone in your home spends on such devices, especially in view of the research finding links with time spent and concentration, learning and memory problems.