Russia is the largest country on earth.
Russian roads are not among the safest on earth. Russians like to drink vodka. And some of them like to drink vodka in their cars. Be aware of drunken drivers. Then again, Russians who own a car are not very probably to be the worst alcoholics and drinking and driving is heavily penalized in Russia.
To increase your safety you might want to hitchhike from police post to police post. The police posts situated on all highways with intervals of about 100 km. These posts, commonly called Post DPS, are good places to hitchhike since cars will drive by slowly, and police is always close. You can also ask the police officers to help you get a ride which really might work.