Sights and Activities of Saint Petersburg
There are many small kiosk around Metro Gostini Dvor and along Nevsky Prospekt street which sells day tours (in english) to all the sights below. You could also book your tours via your hotel. Early reservation is usually not needed, even during summer, as there are many different tour operaters and the competition is fierce.
An example of an excursion booth (Kiosks) along Metro Gostini Dvor and Metro Nevsky Prospekt.
There are day excursion around the city, or day tours to the city outskirts. Most (but not all) the excursions are available in english, so ask in advance about the language spoken during the excursions.
Day Trips out of the city