Forget it. You may feel lucky and try to drive here (or was it "feel lucky to try and drive"?), but you should beware.
First, the lanes are about half a meter narrower. The farther away from a main road, the narrower they get. There was never enough money to do them right, so they were invariably done at some minimal width where two trucks can go by without actually touching each other, at the given speed.
The width isn't the only problem - the thickness of the pavement is another. Technically, there's no problem to build a road which would last pretty much forever; my old street was designed to take heavy trucks into the industrial zone, so it was made by laying 20-30cm large stones at the bottom, then a layer of 10cm ones, then smaller, then pebbles, then three layers of asphalt. It took thirty years to develop the first pothole. However, the regular roads are not done that way, and there's no curb in most places, so the edges are often jagged. The shoulders are often narrow, less than a meter, and they tend to keep puddles in the fall, which then freeze in winter and widen the cracks.
Often, when roads are widened, the shoulders are also widened but not compressed properly, and then they sag, specially in the flatlands in the north, where the soil is softer. Or in the central areas where the landslides may happen ("house on sale, low mileage"). It also happens that they are filled with sand, not stones, and the undercurrents wash the sand away over the years, and suddenly there's a new sinkhole where a whole section of pavement just caves in. Specially around manholes, which are finely level with the pavement only on most important streets. Once you get a bit away, beware.
Also, the roadworks aren't marked as prominently (though it's still better than it once was). You won't see the large kegs stretching half a kilometer around the site. There will be a fence, with proper marking on it, but it may not reflect your headlights properly, may be dirty, so you'd better keep your speed limit right and your windshield clean.
Road signs don't rely as much on road numbering - the country is small enough that you should get oriented by the names of places, and there's usually only one road going to the next one, so road numbers aren't as important, and you won't get an instruction to "take nnn west". It will be "then you take a turn towards Lajkovac". The road signs used to be dismal - frequently missing, sometimes misleading, often vandalized. It's good now, and the main routes are properly marked. The online map is your friend, just like anywhere else. The old printed maps used to have roads which weren't finished yet; now the online maps may be behind the real life. Google may refresh the imagery from time to time, but that doesn't always translate into proper road maps, so it may take you the long way. Consult a local and update your GPS - the people who use it more than I do say that the maps are near perfect.