Serbian (South Slavic)
- +1 Attrition for enemies
- +15% Fort defense
- +1 Yearly legitimacy
- +1 Tolerance of the true faith
- −10% Infantry cost
- +10% Embargo efficiency
- +15% Privateer efficiency
- +1 Yearly navy tradition
- +10% National tax modifier
- +15% National manpower modifier
- +10% Infantry combat ability
Montenegro is a Balkan OPM that does not exist in 1444 except for their core on Zeta, but exists after 1451, save for 1499-1515. It can be released from Serbia in 1444. After 1515, they are an Orthodox theocracy rather than a feudal monarchy. When released they start off next to the Ottomans which is the biggest challenge that Montenegro will face for most of the game.
As Montenegro can be released from Serbia in 1444 it is a good strategy to start as them and destroy the Serbian economy and manpower by disbanding the troops. Go into banktruptcy as Serbia and release Montenegro and play as subject. You should also insult or otherwise damage relations with Bosnia and other Balkan minors so the AI can't ally them. Immediately truce break and take as much land as possible. After Serbia is defeated you can move to Bosnia. You probably wont have manpower after the war with Serbia, so merc up and go into loans. The biggest obstacle is time because the longer you wait the more powerful the Ottomans become, so you don't have time to wait for manpower to recover.
First idea group should be diplomatic as the only friends you will be able to find otherwise are Italian minors which won't help you much in your wars and will likely call you into their wars. After you have taken out Serbia and Bosnia try to attack Venice for Dalmatia if they are at war with the Ottomans. After you take Dalmatia you can focus on conquering Italian minors. By this time they should have already left the HRE, but if not then they will probably leave soon . Alternatively, after taking Dalmatia - as your total development will be rather low - if you improve relations with the Emperor of the HRE(usually Austria so you can start improving relations with them as soon as possible) you may be able to join the empire itself for some added protection vs the Ottomans.