Using a speaker/personal speakerphone or earplug (not wireless) during conversation - distancing the mobile phone from the user’s body reduces his exposure to the radiowave radiation. Therefore, keep the mobile phone at a distance from the body (do not carry it on the body, such as in the belt, pocket or on a neck strap). Obviously, reducing the amount and duration of calls on the mobile phone is another simple measure to reduce exposure.

The World Health Organisation (WHO) released a fact sheet about these issues, shortly after the IARC re-classification, entitled "Electromagnetic fields and public health: mobile phones". The fact sheet points to the findings of the IARC and describes some of the known short-term and long-term effects of phone use, but ultimately, it lands on the side of where the most conclusive evidence exists:
For those of you who experience (or want to prevent) ES symptoms in your hands when using a computer keyboard, laptop, cell phone or other electronic devices, these gloves form a conductive enclosure and effectively shield radiowaves and electric fields. Soft, light weight, with ribbed cuff, and offering good tactile sensitivity. Polyester fiber is twisted with pure Silver fibers, then knit into a stretchy glove shape in basic gray color. Each glove has a 1.7 mm snap for a ground cord. Fully hand washable and tested for 50 cycles with no appreciable loss of conductivity. All fibers are conductive, achieving resistivity of less than 10 Ohm/sq. These gloves are also used in industry for static control when working with delicate static sensitive components and can even be used for TENS applications. Grounding is not necessary for Faraday Cage shielding effect, but is necessary for static control. Also useful on touch screens like an iGlove. We do not have the ground cord which fits this snap on these gloves. Shielded Gloves:
In 2011, the International Agency for Research on Cancer (IARC), a component of the World Health Organization, appointed an expert Working Group to review all available evidence on the use of cell phones. The Working Group classified cell phone use as “possibly carcinogenic to humans,” based on limited evidence from human studies, limited evidence from studies of radiofrequency radiation and cancer in rodents, and inconsistent evidence from mechanistic studies (4).
The energy of electromagnetic radiation is determined by its frequency; ionizing radiation is high frequency, and therefore high energy, whereas non-ionizing radiation is low frequency, and therefore low energy. The NCI fact sheet Electromagnetic Fields and Cancer lists sources of radiofrequency radiation. More information about ionizing radiation can be found on the Radiation page.