Funding an army is no easy task unless you're the most feared pirate of the sea. You'll piss (really? that was censored? It basically means "upset") people off, sure, but they can be bought. Having only played a short time, I can't say that this is entirely comprehensive, but it's worked for me. I've made enough gold that I can simply buy my enemies to death using my patented Currency Redistributor™ (cannons). Traders and pirates are so overjoyed at this newfound wealth that they'll even give you control of their ships.

I'll be sure to update if I come across anything new.

So you just created a new character. If you wish to go the path of a pirate, you'll be needing at least rank 2 in looting. There's a trait you can get called Sutler which doubles the resources you gain from successfully boarding an enemy vessel.

Whether you're a trader or a pirate, your first goal should be to make a bit of money, and to obtain a few ships. You'll need ships for fighting, and for their cargo capacity. Attack weak enemies, and don't anger any nations if you can avoid it.

Don't buy ships. Switch to grapeshots and pick off their crew until they've got as close to 0 as you're comfortable with, then board them. Capture them, then keep or sell.

I've found that the quickest money at this level is selling captured ships, and ripping off other captains. Keep in mind that the latter will give a negative reaction from the captain you're stealing from, and the nation he's from. Don't do this to anyone from the Brotherhood of the Coast. This is because you can increase relations with all nations except them when you kill off Pirates, Smugglers, and etc.

To rip off captains, you'll need the quest Deliverence. It's the one where you've got to aid a crashed ship of theirs. If a captain doesn't give the quest immediately, go back and ask again. As of writing, unlike Warband, if you keep asking they'll eventually give you a different quest.

Go do the quest, be the hero, and then after the battle you'll get the chance to ask what was so important about their shipment. Ask them. Take it. Instead of getting 15k for completing the mission, you will recieve 30k and some negative relation. After which, you're probably going to want to kill a bunch of smugglers and such to bring yourself back in to their good graces, or if you happen to meet a captain of that faction that isn't trying to sink you, you can throw him a few coins to reset it to 0.

After you've got a couple boats to carry your stuff, and have upgraded your flagship to hold its own, it is time to seek profit in war. Not your war, not if you can help it, but from the conflict of others.

What you need is a Letter of Marque. This gives you permission to attack enemies of whoever you get the marque from. The only penalty for success that I've seen is a slight reputation loss from the faction you've attacked, where without the marque it'd be far greater. Because of this, you can get away with privateering against a faction that you've already got a high reputation with, or you'll just need to constantly patch things up. If you're successful, the cost of peace is merely a drop in the bucket.
Do not form your own faction if you wish to remain a privateer. The Letter of Marque quest is failed once you do, and I haven't been able to get it back without a reload.

If you need to fix relations, find an enemy captain. Hopefully, he's incredibly outnumbered by you, but if not then you may attempt to negotiate with him. Let him pick a fight with you, then tell him that you don't want to fight. He'll ask for some money. Pay him. Then talk to him again and say you'd like to patch things up with his nation.

Anyway, you'll be wanting to attack convoys. The ships I suggest you capture are Carracks. They're slow, but make up for it in cargo space.
Remember, get Looting to at least level 2 and unlock the Sutler trait. Convoys give you a lot more loot than a smuggler will, and this trait doubles it.
Board those boats, slay their remaining crew, and take it all. Capture the Carracks. They're worth a pretty penny, but you'll need them for their cargo. Scuttle anything else.

After a bunch of pirating, I started trading with 5 Carracks and some speedy ship as my flagship I had captured.

I later was able to work my way up to capping those 1st Rate Frigates (is that what they're called? You know, those monster ships that mayors run around in. Don't feel like running the game right now). Those ships wreck everything.

So you've got your cargo space, and a bit of dosh, or perhaps just a bunch of junk that you're looking to sell off. Taxes are pretty annoying aren't they? Don't you wish you could find a way around that? Haven't you ever snuck food in to a theater?

Go to any tavern, and in the back right of it you'll find a Suspicious Man. Ask him about smugglers and smuggling. Then, take your loot, or hell, if you've got the money and space just buy anything in bulk, and find the town. Get near the town, right click it, and select "Search for smugglers." Be aware, this is dangerous. Sometimes a patrol will catch you, and you'll need to deal with them. If you get away with it, or save scumm, you can sell your goods without paying docking tax, and for a premium.

I don't have any points in that trading skill, and I can buy some stuff, and resell it for about triple the amount. I load my boats with purchased resources for probably 30-100k, then sell it for 90-300k to a smuggler. Even better if you get that free from looting convoys. This takes 300-900 cargo space for most goods.

When you get enough, head south for the towns that have silver and jewelry. I just made 540k down there!

Whatever you do, remember...