Although it is easy and cheap enough to get there by yourself on public transport many people prefer to arrange to go with a tour group to eliminate any hassle of having to wait for a bus/train and to see all the sites in as quick a time as possible. The most popular and exciting way to get there though is by hydrofoil right from the city centre.
By bus: From Leninsky pr. metro station: marshrutka 103, 420. From Avtovo metro station: marshrutka 224, 300, 424, 424a or public bus 200, 210. From Baltiskaya metro station: marshrutka 404. From Pr. Veteranov metro station: marshrutka 343, 639b.
By hydrofoil: The Meteor speedboat leaves from Admiralteiskaya nab. 2 (Pier with Lions) near Dvortsovy (Palace) Bridge. The hydrofoil comes directly to the Lower park of Peterhof. Departure St. Petersburg - Peterhof: 10:00 - 18:00, every 30 minutes. Tickets 400 - 1,500Rbl.
By train: From Baltisky train station take a train to Novy Peterhof (bound for Oranienbaum or Kalishe). Once in Novy Peterhof, take buses 349, 350, 351, 352, 355, 356, warn the driver that you want to exit next to the fountains.