The main types of train cars
1. First class (SV, business class)

First class car has 9 compartments (coupe), for 2 persons each. In a compartment, there are 2 berths to sit or lie on, and a table between. Luggage can be placed under berths. Compartment door can be closed. At each end of every car there is a bathroom with WC and water basin.
First class in a seating car (usually in express trains) has a
table and extended room for legs. Seats rows are nearly the same as in an airplane.
2. Second class (coupe, economy class)

The difference with the first class is that there are 4 berths instead of 2: two lower and two upper ones. Luggage can be placed under lower berths and to the compartment above the door. The door can be locked. By the window, there is a table. Each car also has two bathrooms. 36 people can travel in such a car at the same time.
The second class in a seating car does not have tables; seats rows are nearly the same as in an airplane.
3. Third class (platzcart)

In a third class car, 54 persons can travel at the same time. Compartments in such cars are open, there are 4 berths in each plus 2 berths over the corridor. Luggage can be placed under lower berths and on 3rd berths, specially designed to store luggage. Each car has two bathrooms. Traveling in the third class is less comfortable than in the 1st and 2nd, but much cheaper.
In every car, there is a conductor. Some trains have a restaurant car.
The availability of the mentioned classes can be different depending on train and destination.
Train tickets

Train tickets for domestic trains can be purchased not earlier than 45 days before departure. For international trains it is 40 days, for some express trains even less.
This can be explained by changes in a timetable and prices, taking place from time to time.
To purchase a ticket, information about the name and passport number (the number of a certificate of birth) of a passenger is needed. Tickets can be purchased by passengers themselves (then, passport itself is to be presented in most cases) at Russian Railways ticket offices, usually situated at railway stations, or with the help of train tickets and travel agencies. It can be difficult to get a ticket close to the departure date, especially in high season.
In a ticket, information about a passenger and his route is provided.
Traveling

Boarding on a train usually starts 20-30 minutes before departure. At the entrance to a car, conductor checks ticket, and maybe passport.
Depending on terms of your ticket, you can have your bedsheets and breakfast prepaid or not. In first class cars in domestic trains they are usually included, and you will find them in your compartment. If not, you can pay to the conductor. Conductors also sell tea, coffee, mineral water.
In Russian trains, conductors may not speak English, but usually there is no need to communicate a lot.
Due to sanitary reasons, bathrooms get closed in approximately 30 minutes before arrival to the destination and on major stops on the route.
Safety.
Generally, Russian trains are safe and tens millions of citizens and guests
use them to travel every year. Police units can go with trains, as well as
ensure security on railway stations. Still, avoid leaving your belongins without notice, keep your valuables in a safe place and beware of doubtful contacts. In the case of an incident, you can appeal to a conductor, police, your travel agent, consulate or embassy.