Water quality varies widely in Russia . Your best bet is to drink and brush your teeth only with bottled water. Be careful to avoid ice and raw foods and vegetables.
With the demise of the Soviet police state crime has been rising throughout Russia , however, it is still safer here than in many American cities. Precautions include not flaunting valuables, or walking alone at night through city streets or parks.
In Russia, taxi fees are usually negotiated with the driver ahead of time. Do not use gypsy cabs or accept rides in cabs that already have a rider.
Tipping is increasingly expected at restaurants. Tip 10-15% depending on service.
Electricity throughout Russia is 220 volt/50 hz. The plug is the two-pin thin European standard. Be sure to bring your own converter as most places in Russia do not carry them.
Remember to bring any medications you may need. Check with your health insurer before you depart to ascertain your coverage in the event of emergency. Many insurance providers offer specialized riders which can cover emergency evacuation.