All top tourist sights and central metro stations in both cities are notorious for pickpockets. Be extra careful.
Be sure to bring an umbrella. According to the latest research, St. Petersburg boasts a pathetic 30–40 cloudless days a year.
Consider staying in one of St. Petersburg's more than 200 mini-hotels—small, 8- to 10-room guesthouses that offer an intimate alternative to the city's major hotels. Most are centrally located, reasonably priced, and if you travel in a group, you could have the property all to yourselves.
Alcohol counterfeiting, which can lead to alcohol poisoning, is a problem, so try to purchase vodka from a reputable-looking store or, if buying from a kiosk, check to see that the seal hasn't been broken.
In some museums, galleries, and palaces, such as the Tretyakov Gallery, you may be asked to put on plastic booties, similar to the kind surgeons wear, over your shoes before entering the gallery. When entering a Russian home, always remove your shoes at the entryway.