Look for a sharp change in the speed limit just outside villages, towns, or any built-up area and obey it. Another signal to watch out for is the flashing headlights of oncoming cars - a common way to warn drivers about to pass into a trap. This scenic, slower route can be quite engaging for you, but not necessarily for your car. Also, be on the look-out for horses, tractors, and pedestrians, especially the staggering kind. Finally, you need not worry about gas unless you plan a long trip into the depths of Poland.
Gas stations are quite common now, and offer most types of fuel.
An unfortunate experience you'll want to avoid is theft , on the train, the bus, or on the road. On the train , this particular evil is common on the international routes, on the express and inter-city trains, and while getting on or off the train. On the bus , it's more a passive pickpocket thing than the aggressive muggings infamous in the States. Take all the usual precautions travellers are advised about the world over, and you'll be okay. Last but by no means least, car theft is quite popular in Poland.