Documents and regulations
All the countries except Russia are Schengen countries, that is there are no regular border inspections and people from most of Europe do not need any visa. However, authorities may stop your vehicle in order to check your travel documents and the registration documents of the car. For entering Russia, a visa is required (see: Visa policy of Russia). More information about entering the individual countries are to be found in their articles. Travelers should observe that it is mandatory to have a first-aid kit and a fire extinguisher in the vehicle in the Baltic countries. Good maps are invaluable especially in bigger cities.
Apart of occasional roadside diners, there is almost always eateries in the towns and cities you'll pass through. Visitors from Western Europe will probably find eating out in the Baltic countries affordable, with a meal and a beverage often well under €10. If you still want to cut your costs, supermarkets and grocery stores are easy to find.
There are hotels and camping sites along the road. Also, you'll find some kind of accommodation in most cities along the road.
Germany, Estonia, Latvia, and Lithuania are part of the euro area. Poland's currency is the złoty and Russia's is the ruble. It is advisable to change some money before the trip. In some hotels it is possible to pay with euros. The price level is lower than in Western Europe, however imported goods of international brands cost roughly the same as everywhere else.
Generally the Baltic countries are safe as long as you use your common sense. Car thefts and burglaries are unfortunately more common in this part of Europe, but as long as you don't leave any valuables on display the risk is small. In the night it is also good to choose a hotel with guarded parking or a camping. As elsewhere in Eastern Europe and in Poland some people tend to drive fast and take great risks, sometimes there are four cars beside each other on a two lane road. The best tip is to keep calm and drive on the right side, however, one has to look out for pedestrians and bikers.