First of all, here’s good news:
It is possible to come to Russia without preliminary bureaucratic procedures with visa. If you are coming on a ferry to St. Petersburg then you can get 3 days (72 hours) visa without filling any documents for visa in advance.
Also starting from 16.04.2011 Turkish citizens can come to Russia without visa for 30 days (but if you plan to stay longer then you have to prepare the documents for longer visa).
Plus currently it is strongly discussed between Russia and EU countries for 30 days free without visa. Before that was only rumors but now it’s a fact that protocol between Schengen countries and Russian Federation are in final stage of negotiating.
For other occasions please check with closest Russian consulate for consultation.
In case you are not from Turkey or you want to see the whole country then you would need more than three days. First of all you should decide which visa type you are going to make.
It’s also important to know that usually you cannot change visa type or prolong your stay while you are in the country. You can apply for prolongation of visa but mostly it’s related to business, student or diplomatic cases.
See also Types of Russia Visa, Documents required for different types of visa
You don’t need Russian visa if…