There is local train service, operating from Bar, through Podgorica and Kolašin and Mojkovac to Bijelo Polje. It is the fastest and cheapest way to travel from north to south, but not so frequent as buses. The quality of service varies, from old noisy Soviet-made electric units to a clean renovated cars with air conditioning. International trains to Belgrade consist of mix of Serbian and Montenegrin cars, the Montenegrin offer generally a better quality.
From fall 2013, there is a new connection between Podgorica to Montenegro's second city Niksic with brand new state-of the art carriages and a renovated track, in a spectacular scenery.
Montenegrin railways have recently updated June 2013 website (http://zcg-prevoz.me/) in Montenegrin and English, there is a searchable timetable Red vožnje on the home page and price overview for a connection. Tickets can be purchased on board.
Roads from Podgorica to Bar and to Niksic are fairly good and easy to drive on.
The roads from Podgorica through Cetinje to Budva and to Petrovac are both in good condition, but are curvy mountainous roads which rarely permit speeds over 70km/h.
The road from Podgorica north to Kolasin, and then on to Zabljak or Serbia, is considered dangerous during the winter, especially the part through the Moraca canyon. It is recommended that one takes the bus to the north during the cold or rainy days, as bus drivers are experienced and know the road.
The old road from Cetinje to Kotor is mostly a narrow one-lane road offering stunning views of Kotor from above, but exercise extreme caution when passing on-coming traffic, over-taking and around corners.
Montenegro has no motorways; most roads have only two-lanes with the frequent addition of a third lane for overtaking, and generally are not up to European standards, although in the past few years many of the main roads and tunnels have been renovated and are quite safe as long as you are not driving recklessly. Most roads are curvy and mountainous, so speeds over 80 km/h 50 mph are rarely legal, and rarely safe.
The speed limit is 80 km/h on the open road, unless signs specify otherwise. The speed limit inside the cities is 50 km/h.
The use of safety belts and headlights during the day is compulsory, and the use of cellphones while driving is prohibited. Signposts used in Montenegro are almost identical to those used in EU countries.
Local drivers tend to drive fast, and to get involved into dangerous overtakings. Traffic jams are common during the peak of the summer season. Pedestrians are notorious for jaywalking in every Montenegrin city.
Drivers tend to be extremely vocal, so don't take it personally if a driver yells at you.
This may be the easiest way to get around Montenegro. Buses are frequent especially during the summer, safe and are more or less on schedule. Local buses usually have no airconditioning.
Ticket prices within Montenegro are all under €15. Buses to attractive tourist destinations Budva, Kotor are generally more expensive up to 2 times more per kilometer than others.
Examples of prices: Podgorica–Ulcinj €6, Podgorica–Cetinje €3, Podgorica–Kotor €7, Podgorica–Plav €11 Aug 2012.
Besides the buses, there are minibuses at bus stations that are usually slightly cheaper, but are actually a faster and more comfortable option.