Ground transport operates in St petersburg from 6 a.m. to 12 a.m. 
Bus stops are indicated by square yellow signs marked with the letter "A".
 St Petersburg city bus
Trolley-bus stops are indicated by blue boards with the red letter "

" , they are usually mounted on poles..
St Petersburg city trolley-bus
Tram stops are indicated by boards with a letter "

" hanging on the electric wires.
St Petersburg city tram

There are also taxi-minibuses, which are called "marshrutnoe taksi" or "marshrutki"; they have numbers and route descriptions written in Russian on the side windows. They are much more comfortable than most transport and you always get a seat. You will be charged 8-12 rubles when you board a minibus, then just tell the driver when you get near to where you need to get off that you want him to stop.
.
Taxi-minibus ("Marshrutka")

The cost of the trip in a regular bus, trolley-bus or a tram is 5 roubles and you should pay for your ticket in cash to a conductor on board. At "rush hours" (in the morning and evening, about 6 p.m.) public transport is usually overcrowded. 

You can buy a universal transport pass for all kinds of public transport (bus, trolley-bus, tram, metro) valid for one month (70 trips on metro and unlimited trips by ground transport).