You can go ahead and hire a car for your own trip if you are certain of your driving skills. Based on my experience of driving around with travelers in the cars they had hired I would say that Belarusian traffic rules and signs are almost the same as those in other Western countries. According to my guests, too, Belarusian motor roads are much better than those in Ukraine or Russia and have considerably lower traffic.
Black on white - you are entering a town/ village
Your driving license is valid in Belarus for the first three months which is enough for a simple Belarus sightseeing trip. You can Google for several car rental companies, the partners of the world known brands: Hertz, Europcar and Sixt. However, numerous private providers have cheaper offers, though they are harder to find.
Naturally, language will present the major difficulty since most of the road signs in Belarus are in Belarusian, a few – in Russian, very few – in English.
Most GPS devices supplied by the car rentals will be also in Russian which makes the navigation trickier, although if you are sticking to the main roads, a map with transcribed city names will do fine. And of course you should do your homework with Google Maps.