There are several types of Russian visas:
This routine is usually a great surprise and problem for all foreigners coming to Russia. The thing is that all foreigners visiting Russia must be registered in PVU (Passport & Visa Department) (it is new name of UVIR, Russian abbreviation for the Department of Visas and Registrations).. This registration is responsibility of the firm or organization or a person who invited you and is indicated in your visa. If you came to Russia and were not registered for three working days, the police can fine you for the first time ($10 - $50), the second - has the right to exile you before the expiration of your visa and put you on the "Black List" (you will not be allowed to enter the country for one year). If a foreigner is unable to find the firm indicated in his visa, Russian law says that he must leave the country in three days even if he has one-year visa.
So, the first rule is:
NEVER BUY YOUR VISA INVITATION FROM A FIRM IF YOU ARE NOT GUARANTEED TO ARRANGE THE REGISTRATION IN RUSSIA.
There are a lot of offers of any invitations near Russian Consulates or Embassies, but if a foreigner buys any of it, enter Russia and is unable to register his visa, his Russian visa can be cancelled.
So, the second rule is:
DO NOT FORGET TO ARRANGE LOCAL REGISTRATION OF YOUR VISA AS SOON AS YOU GET INTO ANY NEW RUSSIAN CITY!
Once you are in Russia you may need to extend your
stay there. The official regulations accept only two reasons
for a visa extension:
a return ticket for a fixed date (not later than a couple of weeks after the expiration of your visa); this extension can be performed only once.
a job permit issued for working at a Russian firm; it is a long story (we also assist in obtaining it, inquires are welcome), expenses amount to hundreds and hundreds USD.
So the third rule is:
ORDER YOUR VISA FOR THE LONGEST POSSIBLE TERM!