Set Booty Bay to "At War" in the Reputation tab, and kill Booty Bay guards until honored with Bloodsail Buccaneers.
You can continue until Hated with Booty Bay if you'd like to knock out the "Bloodsail Admiral" title as well, by completing the "Avast Ye, Admiral!" quest to earn your title and gear.
To make your way back up from Hated to Exalted, the fastest way is to turn in repeatable quests.
Ratchet - turn in "Mending Old Wounds" over and over with 40x Linen Cloth and 4x Crystal Vial
Booty Bay - turn in "Traitor to the Bloodsail" over and over with 40x Silk Cloth and 4x Red Dye
Gadgetzan - turn in "War at Sea" over and over with 40x Mageweave Cloth and 4x Strong Flux
Everlook - turn in "Making Amends" over and over with 40x Runecloth and 4x Coal
each rewards 1500 (1650 with human) rep with their respective location, and 750 (825 with human) to the others. These are only available until Neutral with their respective reputation.
You can then do any quests you can find. Most being in Booty Bay, Gadgetzan, and Ratchet in that order. You can find small amounts of rep in Feralas, Dustwallow Marsh, etc. but it's not worth it in my opinion.
Instead, you can turn in "The Gordok Ogre Suit" and "Free Knot!" in Dire Maul North for ~1300 rep total, but may hit the 5x instances per hour limit as it only takes 5-7 minutes per run depending on speed boosts.
For "The Gordok Ogre Suit", each turn in requires 4x Bolt of Runecloth, 8x Rugged Leather, 2x Rune Thread, and 1x Ogre Tannin. The Ogre Tannin is located directly behind the questgiver in a jar, and spawns an add when you open it.
For "Free Knot!", you have to turn in a "Gordok Shackle Key" each time, and they are unique and BoP, so each time you run in you have to farm one from the ogres there. As soon as you get a shackle key, don't kill any more ogres if you can help it, since after turn in you can farm the ogres for another key as you leave to reset.
To start, complete the quest "Elven Legends" if you are Alliance, or "Elven Legends" if you are Horde, which requires you to inspect a skeleton in Dire Maul North Library.
After completing that, return to DM:N Library with Libram's and these mats, and you can turn in repeatable quests for 1500 rep each (1650 with human racial):
28 (26 with human racial) Libram's (Protection, Rapidity, Focus) - Rapidity/Protection are easiest unless you have scholomance key.
28 (26 with human racial) Pristine Black Diamond
56 - 112 (52 - 104 with human racial) Large Brilliant Shard (Depending on which Libram you use, Protection/Rapidity is 2 per quest, Focus is 4 per quest.)
I would suggest gathering your Libram's first if you can before buying shards and diamonds so as not to overspend on mats.
Each Libram as well requires a BoP item to be turned in, and can be farmed in these locations:
Libram of Protection - 1x Frayed Abomination Stitching (Farmed in Stratholme)
Libram of Rapidity - 2x Blood of Heroes (Farmed in Eastern Plaguelands) These are the only spawns I could find after several days of running around EPL.
Libram of Focus - 2x Skin of Shadow (Farmed in Scholomance, 1 guaranteed per run and others rare drop.)
These Libram's may be hard to come by since the AH barely has any due to them being useless outside of this achievement. That being said, when they are on AH, they can be anywhere from 10g - 400g. They also drop from level appropriate dungeons such as Stratholme, Scholomance, and Dire Maul.
Also, each one is Unique, so you can only have 1 of each in your inventory at a time. This is where Engineering or a friend with Engineering comes in handy. Buy all of them on an alt, then include 1 of each in a mail to your main and send them. When at the questgiver, put a MOLL-E down and open each one as you turn them in for maximum efficiency.
Go to Durnholde Keep in Hillsbrad Foothills, and kill every mob for rep until Revered. A full run through of every mob grants roughly 1k rep.
Then head to Ravenholdt Manor (Coordinates to entrance at 75, 23) and turn in "Junkboxes Needed" from Revered to Exalted, you'll need 470 (430 as human) to reach Exalted. Either buy them (rarely, if ever, found on the AH. Best place to farm in my opinion was Blackrock Spire. Side note, if you are a rich individual, you can buy your way from Neutral to Exalted purely through junkboxes. You will need 940 (860 as human) total to do this method. I do not recommend it though as you can constantly be rotating around Durnholde for free with little downtime. In total I think it took me 3-4 hours grinding mobs to Revered.
This is also the only way to do this rep.
Wait for a Darkmoon Faire (1st sunday of every month) and turn in simple crafted items such as Dense Grinding Stone, Thorium Widget, and Rugged Armor Kits, and Darkmoon Card Decks. The only ways of obtaining Darkmoon decks is buying them from other players, or making thousands of Darkmoon Card of the North through Inscription, which requires many, many herbs. Farming herbs yourself and making cards yourself is, of course, a much cheaper option, but it is incredibly slow.
Easiest way I've found is to buy 70 "Dense Grinding Stones" up to 2775/6000, and then turn in epic decks. From this point to exalted you need a total of 35 decks (32 decks if human)
Add 1 deck more to each if you want 999/1000.
In conclusion, this title is going to take a LOT of gold, or a LOT of time. In my opinion it's worth it since you don't see it too often due to these reasons.