General Tips: dominate some trade (don't get knocked out/embargoed), keep your head down, ally larger nations, and be sure to gift and access your enemies so you at least get a warning before you are attacked; if not, they take a hefty stab. Be wary of the AI's ego and be sure to pounce on opportunities: being too cautious will make for a boring game.
As the Knights in my current summer multiplayer game (start 1399), I relied on my Guarantees and being in Castille's sphere of influence to deter the Ottomans, Venice, Naples, and other hungry nations. To preface: the other nations are Sweden, Brandenburg, and Switzerland. Two are landlocked and Sweden wanted to become Scandinavia->Scandarussia. Everyone thought I was going to be knocked out in the first few years by the Ottomans.
Also: Portugal was landlocked at one point and did not choose QFTNW as their second NI. Castille went a different route as well, since they were concerned with constant BBB wars. I did mint a bit, but always brought it back down.
For a good opening, ally the Papal States and Aquilia right away. Convert your ruler to a general. Put them into your cog. Ask Achea for Access. DoW on the Byzantine Empire after they have gone to war with Karamon or Candar (October 14th). Invade Morea and CtA the Papal States or Aquilia. Your ally will invade Thrace. Take their ducats and Morea. Keep your men in Morea, because you can only have one.
Take the Alexandria CoT. Not much European competition. Wait it out and pump Government to 4. Grab Unam Sanctum. Then pump Trade to 7. I was able to get a Core on Malta, Crete, and Cyprus via Missions and Events. I gifted, guaranteed, accessed, then allied with the Ottomans for a bit to take those territories. Whenever you have the chance, DoW on the Byzantines every time they try to free themselves. Spend your time building Workshops on your Wine provinces, raiding Georgia, or Settlement Policing to have Maltese everywhere.
By the time I had Morea, Crete, Rhodes, and Cyprus, I had a few Carracks and a few cogs. I loaded them up and DoWed on Sicily who were allied to the Papal State after they had lost in a war to Milan and Aragon. Naples DoWed Sicily a month after me and helped clean up the Papal States while I grabbed Malta. The Ottomans broke our alliance. This was around 1435. I left Castille's SoI and they allied me. I chose Colonial Ventures as my second Idea.
I switched ideas to QFTNW and snatched both Cape Verde and the Canaries. By this point, I had 8,000 soldiers. I asked Castille for military access and began to explore the new world. This took more time then I anticipated and took Kozani back in the old world. Once I found the Mayans, I sent 4,000 men down with a Conquistador then ferried over the other 4,000 while the Conquistador explored Central America. During this time, I used my Carracks back in the Old World to help Castille fight whomever, while they gave me war subsidies ranging from 9-10 a month.
I invaded the Maya and took four provinces and 2,000 ducats. I occupied the four with 2,000 stacks until the Forts were done then made 4,000 go home while I built more troops to ferry over. After Forts were done, I immediately began conversion. It was 1450. Over the next 20 years I was in 3 more wars with the Maya that earned my growing empire 3,000 more ducats and all their provinces. I was lucky enough to get Cores on Petan and Mexico. I moved my capital to Mexico. I chose Land of Opportunity.
Now, I am colonizing Northern South America and connecting to the Inca, were I have done two raids and earned 2,500 ducats. It is important to have 1,000 laying around for carpet colonizing. I now have 34 Catholic Provinces, mostly Maltese, and I am almost connected to the Inca. Ottomans are still on Great Relations and trust me utterly, Castille is being slowly torn apart by France but trusts me utterly, and I allied with Naples for some Mediterranean domination. Though, I am suffering some serious over-extension. Unavoidable in my case, because I think Portugal, Great Britian (minus a 3 province Tyrone), and Castille will take QFTNW as their third NI. My fourth, which I should be getting in 1510ish, will be Church Attendance to stave off the Reformation.
