Every culture has its own поверья (beliefs) and суеверия (superstitions), which help us understand more about its history and the relations people maintained with their environment.
Русские весьма суеверны (Russians are very superstitious), which is not surprising with so many past and present uncertainties. They tend to use everything in their power чтобы защитить их от неудач (to protect themselves from bad luck) and принести им счастье и удачу (to bring them happiness and fortune).
The Threshold of Your House Is the Devils' Home
I doubt that you will ever see two Russians shaking hands or even talking через порог дома (across the threshold of a house), as it is said to be the place where devils live. Nor не ставь на стол пустые бутылки, ключи и мелочь (don't leave empty bottles, keys or small change on a table), this would bring financial misfortune and tears.
Remember also when you are paying in a shop, to put the money on the little plastic tray. Не давай денег в руки (don't give the money directly in the person hand) as it is believed that money carries the holder's energy, good or bad, and who wants to take the risk?
What to Do Before Leaving
Before you are going away for a long journey, make sure you and everyone in the house присесть "на дорожку" (sit down for the journey). Someone will say "Присядем на дорожку" (Let's take a seat for the road) and everyone has to seat and be quiet for a minute. This will keep you from bad luck.
It is also bad luck ходить с пустым ведром (to carry an empty bucket), or to meet someone who carries one. You can be sure that you will have a bad day.
Omens are Good Messengers
Getting a haircut when a member of your family is in danger is a bad примета (omen), but can tell a lot. As an example this story back from 1996. Борис Ельцин (Boris Yelstin) underwent a bypass surgery and the all country was expecting news. Soon after his surgery, his wife made a public appearance with a new haircut, a clear message to all Russians that her husband was recovering.
There are still many more superstitions. However, don't be surprised to get room 13 in a hotel, or to find out that your friends are living on the 13th floor. There is no such a superstition in Russia.
