Tips for Moscow

The first thing you have to know about; is the registration. Once in Russia you have to register your visa. Depending where you are, it will cost you 300 to 600 Rubles. Do it only once. At the hotels they will say, you have to do it every time you stay more than 72 hours in the same city. It's true but if you don't do it, it won't be a big problem to leave the country. The only time you may "need" it, is if you get checked by the police. They never check the tourists, you really have to look like Ben Laden to have problem with those guys. It's just a good opportunity for the hotels to make money from foreigners (which is actually a rule in Russia).

Trains:
If you want to buy train tickets, and you don't speak Russian, ask the staff at you hotel to write down a note with what you need. Write down as many train numbers as you can, because if the train you want is full, the won't look up by themselves for an other one, even though they might be several still not full.
Depending where you want to go, you need to know which station sell tickets for your destination.
The train station for Irkutsk and St. Petersburg is Komsomolskaya on line number 1 (red line).
For Riga, it is Rizhskaya on line number 6 (orange line).
If you don't want to struggle buying the tickets yourself, because it can be annoying, you can go on www.waytorussia.com, they will arrange the tickets for you, and you just have to pick them up either at their office or at the train station.

Hostel:
The one I can recommend is Godzilla's hostel. The place is clean, the staff is friendly and the location is very convenient. The metro station is only 5 minutes walk from the hostel. It is situated in residential area so, if you are a party person, maybe, this won't be the best hostel for you, at night it's very quite and also very safe. The place is non-smoking, smokers go outside to smoke their cigarette. If you feel like, the hostel is a walking distance from all the majors sightseeing (30 minutes walk).