I have played this game since it has gotten dedicated servers, seen it fall from top 10 to sometimes 0 lobbies, Suicide Blink Days, the rise, fall, and return of Queen Anne's Revenge, seen Wasa Gaming. God of Storm, and now we're here.

Some of you may know "dangerman".

This guide is my build for playing with mostly strangers, and a lot of general/quick notes on many noteworthy items. Comments and Criticism appreciated. :)

Starting items:
3 Stone Shooting Machinery

Save skill point in case HMS bounty is seen (then put into hull or artillery, usually hull)
usually put second point into regeneration. artillery is lowest priority unless playing agressive with teammates.

Start going back to base at ~2:40, arrive in dock around 3:00 and upgrade ship.

Alternate:
HMS bounty + choice of any 200g item (suggest small repair wood).
Attempt to suicide on ships.

3 minute items:
HMS bounty, Machine crossbow/flintlock, Latreen, stone armor plating, maintenance crew

If survived laning without dying and got a few last hits, should have enough in a 5v5 game to buy all of these.
Sell SSM if necessary to buy items.
If have extra money, consider buying Senior Maintenance crew or buying a Pirate de Iles (and don't buy stone armor plating)
Stone armor plating + HMS bounty + 1 hull is 650 hp, enough to survive level 3 suicide charge. 2 points in hull is 750 which is very safe.

6-12 minute:
Get a second machine crossbow (suggested, but optional), and a senior maintenance crew.
Buy the God of Storm when possible, best at almost level 10 or at level 10. Most points into Storm and Holy Scourge, 1 point in Dark Clouds, as many in regeneration and sail.

With this, you can start diving. Skill build goes prioritize Dark Clouds, the aoe miss becomes better as more points are put into it. May put more points into Storm if it doesn't kill the creeps.

Early Items/small:
Stone Shooting Machinery (200g): high dps with good range. 3 of these makes a solid start.
Light crossbow (180g): low range makes it dangerous to farm with. Same range as suicide charge.
Stone Armor Plating (175g): 150 hp is enough to survive some levels of Suicide Charge. The HMS bounty with 1 level in hull and this item can surivive a level 3 suicide charge (650 damage vs 650 hp +5% reduction)
Maintenance crew (180g): 5 hp/s isn't much, but it is effectively a skill point worth.
Flintlock (800g): 100 burst damage is great, two of these will 1shot a single small creep. Outranges towers and the machine crossbow. 4 of these will kill an unarmored HMS Bounty or Sailboat
Machine crossbow (990g): Absurd dps for its cost and decent range, this is an excellent item in general.
Senior maintenance Crew (800g): 15 hp/second is enough to sustain most any light fire.
Fire Crossbow/Fish Spear + upgrades: Are okay, simple, good dps, short range weapons. Upgraded versions sell for 1/2 upgrade price, not full price.

Alternative Early/Mid-tier ships:
HMS Bounty (500g): nice hp for cost, good first upgrade from basic ship if only just for HP. Also nice damage. Net is a one-point wonder.
Nina (1200g): This is a slow ship, but has a repair over time ability.
Pirate De Iles (1800g): Long range instant silence can counter many plays. Exile is a disruption as well, stops channeling abilities. Very strong support ship.
Beagle (2600g): A very strong support ship, can give total physical damage immunity.
Golden Hinde (2200g): Instant aoe silence can counter multiple iniations.
Wasa (2000g): Global ranged single target stun can make unexpected plays. Gold Forged makes this ship able to duel glass cannons, as well as initate as a sacrificial lamb.
Ghost (3000g): Free damage and concentrated fire make this ship good at killing players. Cast Concentrate Fire AFTER spawning the illusion.
Xebec (3000g): The first long duration single target stun. Doom seems to increase damage taken by target ship by 100%. Long cast points make this ship not great at initating.
God of Storm (3500g): A few points in Storm and this ship can kill the medium creepships. First ship to have high base hp and movement speed.
Endeavour (5000g): This ship has a global gold aura, and can kill almost entire creepwaves with a single ability. Also fairly survivable.
San Felipe (5500g): First great aoe stun, lasts up to 7 seconds. Has high healing. Good blink-initator.

Mid-tier items:
Senior maintenance Crew (800g): A second one will stack fully with the first, the HP regeneration becomes comparible to a Thetis Harp.
Siren Scale (2600g): 1800g more expensive than just a Senior Maintence crew, the bonus 30 speed is amplified by +ms.
Compass - Durable (1800g): A blink is sometimes necessary to escape from some boats. Consider getting if enemy team has heavy: Wasa, Xebec, San Felipe, Wyad Gally, Soverign of the Seas, Queen Anne's Revenge, Black Pearl. Get the speed compass instead if you do not have Siren Scale and are being chased down.
Compass - In Full Sail (1800g): Has bonus speed instead of extra regeneration.
Regular Repair Wood (650g): 1.5k burst hp can help, sometimes.
Thetis Harp (5300g): 50 hp per second makes a ship immortal to light fire, and heals ships baack to full. Very expensive for what it does though.

Cannon of Faith (4000g): Cheesiest weapon of cheesy weapons. Only hits heros (does not target creeps nor buildings) and has decent range, can be bought within the first 6-9 minutes and kill everyone. Has exactly 0 farm ability and is entirely snowball. Falls off fast.
Star Cannon (5000g): 800 range, enough to outrange towers, and always hits ships that're in range. Guarenteed damage, unlike most other weapons which lose 1/2 their dps when there's a tower and a ship or even more. Weakness is average 1v1 DPS for price.
Essence of Storm (5500g): an okay-hitting weapon overall. Has a minor slow, but its firerate makes it unreliable.
Guardian Cannon (4460 + guardian cannon 1): mathematically OP and works great when multiple heros get one, as the range is long. 300 units longer than night-time vision. An exceptional weapon that outdps (considering range) most every other weapon up to twice its price cost. upgrading to Leviathan Cannon is a downgrade/bad use of gold.


Next steps:

Ships:
Royal Fortune (6200g): A fragile ship that has the greatest damage potential. Also has an instant silence. Has mediocre hp for cost and is slow. Good when balling out of control.
Soverign of the Seas (6500): Its stun is non-disjointable. It utli deals additional damage to the stern of ships, as far as I can tell. Good hp for cost. Also fast.
Queen Anne's Revenge (8200g): The longest instant stun in the game. The only disarm. Ultimate is very strong, but requires mobility. Fast ship, mediocre hp for cost. The best pickoff and skirmish ship. Multiple QARs on a team is very scary.
Flying Dutchman (7200g): A ship that has a lot of features - aoe burst, aoe stun, two mobility skills, a slow. But is mediocre at all of them.
Zhenghe (6000g): The teamfight ship. Has damage amplification and reduction auras, as well as a heal for 21% of allies max hp.
Quedagh Merchant (8500g): One of two ships to have magic immunity. So fast that it hits max speed with just a latreen and passive speed.
Le Soleil Royale (7000g): An impressive heal aura ship, strong teamfighter and seiger.
Fantasy (6200g): A theoretically strong ship. In practice, postioning for its channeled abilities is difficult. When played well, it can make great plays. Up to 13 seconds of total invulnerability to damage and spells for all allied units (except the caster and units under the caster's control) is a huge turn.
Black Pearl (16000g): The Ultimate teamfight ship. Has the most potential aoe burst damage, has 2 damage reduction abilities, 1 of which is an aoe buff and speeds allies. The most hp of any ship. Cast Gods Asylum before blink-initiating to improve damage and survivability.

Weapons:
Cannon of Corruption (12000g): A very strong mid range weapon. It's almost a Venomous Gale. Hitting a ship just once with this will deal over 400 total damage. Good for slowly attacking towers as well. Corruption debuffs do not stack, having more than one (including from allies) has lower efficiency. Very good at kiting and harassment.
Wuhou's Machine Crossbow (13500g): The highest single target dps weapon in the game.
Flame of the Phoenix (14000g): The AOE damage on this makes it the ultimate weapon for farming waves and pushing. It melts and entire wave of small creeps in 1 shot, and 3 shots the large creepwave. It is also excellent for teamfights due to its high aoe damage. Burn debuff does not stack, having more than one (including from allies) has lower efficiency. The burn radius is massive, it can burn enemies up to 1300 range away from the ship (assuming nobody moves). Can be used to absolutely suck up farm.
Cannon of Tide (11500g): Very high pure dps for a mid-range weapon.

Defense/Utility:
Fish Keel (7200g): The ultimate defense item, 40% damage reduction and 1000 hp. The speed reduction is not a huge deal if enemies are locked down or you're gaining a buff from an ally (Black Pearl's Pirate Union or Zhenghe's Everything Goes Well).
Skin of Seven Head Snake (7400g): for those who don't want the speed reduction of the Fish Keel, this one can free up a slot by replacing the player's sail.
Compass (1800g): both are strong, the speed compass is slightly better for the extra move speed across the map. The 5 regen is very minor compared to EHP of players and their DPS.