My friend was recently spending two weeks in Moscow for the first time and visited many places of Russia with English-Russian tour guide. He booked 8 days
Russia tour and visited all the places with a tour guide, so you can try that way.
He said in the tour package, 6 nights accommodation, sightseeing and service of an English-speaking tour manager throughout Russia were included. He has visited Armory Museum(Moscow),
Hermitage Museum(St. Petersburg),St. Sophia Cathedral(Novgorod), Peter and Paul Fortress(St. Petersburg) and some more places.
Mascow is one the most expensive cities in the world, but it's worth to visit,so spend more time in Moscow. Visit the cities of the golden ring namely Suzdal,Vladimir,Zagorsk and Yaroslav. These towns have churches, monasteries and kremlins. Also have a boat trip on the Moscow river and enjoy the night life of Moscow with good dinner.
Probably you will extend your visa to visit more places, because there are 1000's of sights to see, have a nice journey and explore Russia, best of luck!