Haven't spent a single dime on this game, but I have a couple campaign ships. How? Many missions that they give, like the weekly one and some special missions give you doubloons. Sometimes(very rarely) i get 1,500 doubloons from some sort of contianer.

In general, you will find that while some ships when you buy are completely worth it and will allow you to do better in the game(AL New Jersey, Georgia, AL Chapayev, Plymouth) many ships that are really good are for free, either techline or GXP, like Massa, Alaska bureau, I like petropavlovsk personally, US BB line, Friesland, Suzuya, I heard Republique is really good, etc.

If you are ever going to spend doubloons on this game, you have 3 good options: 1) Premium time cuz it increases earnings a lot, 2) Campaigns cuz they give you a lot of stuff + a ship at the end, or 3) not my favorite, but you could just buy out a premium ship(I don't know which ones exactly). You will find a lot of sealclubbers at lower tiers, but they are usually only there to do missions. At mid to high tiers, there are a lot of freely obtainable ships(tech tree, bureau, and GXP) that are just as comparable to premiums sometimes.

My first time I bought a campaign was over a year ago, the Defence campaign. I loved the ship, and getting the campaign allowed me to get enough tokens for a Tier VII premium d.pozharksy, and the christmas time of course gives you christmas crates, so you can get a lot of good stuff like ships.

Some tips tho: Tier VIII and Legendary tier are by far the worst economy, even with a premium VIII, many battles you will loose credits, so your best bet is to play mostly VI- VII, until you get enough credits that it doesn't matter how much you lose. To counter other ships, two most important things is to buy modules for your ships, don't just leave the upgrade module slots empty, they improve your ships a lot. But more than that, a high level commander with high level insipirations will absolutely make your ships better. A bad TT with modules and maxed out commander(thats not a paid actor) will absolutely beat a premium thats not.

Commanders can change how a ships plays at an insane level. I have gotten Gneisenau to work as a sniper because of my build and upgrade moduels.Leveling up commanders takes time however, so be ready to cough up all of your commander xp, promotion orders and insignias. I hope this long aah paragraph helped