So, your Russian visa has been received and is already pasted into your passport. Most likely, you have already purchased medical insurance and purchased air tickets to Moscow / St. Petersburg. Please note that without medical insurance you may not be allowed into Russia. Also, when entering Russia, immigration officers sometimes ask for a return ticket.
How to book a hotel in Moscow or St. Petersburg under sanctions? Booking.Com and Airbnb do not work in Russia
You can use the largest Russian hotel booking service Ostrovok, which is available in English and accepts foreign cards.
Hotel bookings from Yandex Travel, unfortunately, are only in Russian, but the translator built into your browser will help you. There are selections of hotels by theme. You can find hotels to watch the Northern Lights if you dream of going beyond the Arctic Circle.
Order excursions / personal guide in Moscow or St. Petersburg
Many city tours around Moscow and the cultural capital of St. Petersburg with Sputnik.
You can independently explore the sights of Russian cities with an audio guide in English (there is a mobile application).
The travel app from Trip.com will help you suggest interesting cultural sites and ideas for walking tours in Moscow or St. Petersburg.
On the Afisha website you can get acquainted with cultural programs in Russian cities and purchase tickets to the theater, cinema, and exhibitions.