There are some aspects in regards to mailing letters to Russia which I think you should know:
First, letters coming from abroad are quite often opened by post employees. They unseal the letters without leaving any marks, remove all valuables, and reseal the letters back or simply trash them. It is better to enclose IRCs rather than Green Stamps (which will undoubtedly tempt the post personnel very easy) or send letters by registered mail. The US dollar exchange rate is around 30 roubles nowadays, while an IRC costs 14. I mean it can be exchanged for postage stamps 14 roubles worth.
Second, the post office requires that full name of the addressee should be clearly written on the envelope when you send your letter to Russia. That is because due to a lack of PO Boxes some people are sub-renting them, in order to earn extra money. In order to crack down on them, post personnel will not forward the letters that are addressed incorrectly or incompletely.
Third, don't cross zeros with a slant (/) bar when writing numbers in an address as is commonly done when writing callsigns. Since this is not done in Russia a post office employee will likely think that you made an error and put your letter into a wrong POB.
Forth, don't write the callsign of the addressee on the envelope. The post employees know very well that hams may receive Green Stamps from time to time, and they will pilfer the letters addressed to hams.
And the last, but not the least. Please write address on the envelope as legibly as possible!
After receiving several emails with questions of the same type I desided to create a kind of FAQ on direct QSLing into Russia. If you have any additional questions don't hesitate to ask. Every email will be responded.
Got some Russian stamps. Will it worth to use them for SASE?
Using Russian stamps for SASE is not a bad way out at all. I think nobody of post employees will try to unstick them. Hi. Actually this will not work to QSL managers who try to earn extra money on QSLing (e.g. RW6HS). And keep in mind that postage rates increase from time to time, last time this happend in autumn 2000.
Wouldn't it be better if letters are mailed from inside Russia?
Sure, it will. The delivery will be much safer. Besides that domestic postage rates are quite low here.
BTW if you are involved in IOTA chasing or any other activity that requires frequent need for direct QSLing into Russia, and you have a friend here, you may ask him to help you. E.g. I manage some foreign friends and quite succeed in it.
I've noticed the order of lines in the address is different in Russia. What is the best way to write the address?
I would suggest the following: name, box number (or street address), city, zip code, country. The order was different until recently, but now it doesn't matter much.