After you have gotten back from the Presidio and gotten your new companion, you are tasked with seeking out One-Eyed Jack in flotsam. I would recommend grinding to nautical level 5, if you haven't already, since you are already near those ships and the good equipment you can buy from the shop in Gullet for your new ship requires lvl N5. Also, be sure you go spend the first practice point you got from reaching level 8!
When you get to Flotsam, there will be a bit of runaround which is pretty straightforward (though Flotsam roads are anything but): just follow the arrow. You help out Mustang Sally, who will be joining Swashbucklers much later in the game and rest of us can eventually buy her in the crown shop. This fight is very standard. Just burn down the dog pirates one at a time. You're supposed to protect Sally, but she can fend for herself, so just worry about getting through it as efficiently as you can. As a side note, there are a lot of treasure chests in this room, but you can't open any of them so don't bother trying.
Once you finally meet One-Eyed Jack, you go to where Ratbeard was hiding out. About 50% of the times I did this part of the quest chain, there was a treasure chest sitting just outside the door to Ratbeard's hideout, so keep your eyes peeled! You could get as much as 8-15 gold coins!!! Treasure chests are pretty weak this early in the game.
You are then sent to Corsair's Cove. Make sure you grab the training tome from the table, though it's tough to miss and one of your crew mates even mentions it.
After that, you go to the Lighthouse. You are tasked with locating 5 tombstones. Now, while it is possible to avoid all combat, on the first tombstone, you'll probably get dragged into a fight. If you try really hard (I was only able to do this once out of 6 tries) you can sneak past the mobs on this tombstone, but you have to go around through the fern and then time it just right. Once I had done that on my Privateer, I just warped to the Lighthouse lifestone as I didn't think I'd be able to sneak out the way I came and it would be faster to run back!
Once you enter the Hoodoo House, you can't avoid the first fight there. Make sure you have a mojo potion full, because there is a good chance at least one of your companions will be knocked out on the first fight (which you cannot sneak past, at least I couldn't find a good path). There's no weird strategy, they just hit really hard, so be careful and focus your attacks.
For the Old Scratch fight, Make sure you have 1 or two ranged crew members (or if you are a Witchdoctor or Musketeer, 1 other ranged crew member). You may also want to un-equip your pet. The fight condition is "Defeat Old Scratch" so don't worry about any of the other undead attacking you, just focus on him. The reason for the ranged and no pet is that it's very easy for Old Scratch to get bottle necked on the map, making it impossible for you to reach him with more than one or two of your characters. Get them all close to him, then just wail away as fast as you can, ignoring everything else. Congrats, you've got a new crew member.
Once you're done there, you're sent to Gunn's Island. At the quest turn in, if you haven't done any other side quests or grinding, you will hit lvl 9 with enough training points to promote Bonnie Anne to lvl 8, where she gets her first promotion. At this point, I go ahead and do the promotion quest. It's fairly quick and simple and makes her a lot stronger for the final fight in Waponi Wu.
Back at Gunn's Island, you have a little more busy work, then you fight a bunch of crabs. A standard fight, though the crabs can hit hard so be careful! Once you've done that, on to Waponi Wu!
You have to fight some water moles before you can enter the instance. I would recommend focusing on the Witchdoctor types first as they have a strong area of effect attack. Also, on the right hand side as you run through the very first Water Mole area, there's a training tome on the ground by one of the huts. I missed this on 4 out of 5 runs through this area. That reminds me, I'll have to go back with my other characters and pick this up!
Once you go in the instance, the first fight is against two gold fish who are a huge pain. It's just you and your first mate, so make sure if you are ranged, your first mate is melee and vice versa. It is very easy to get bottle-necked in this one as well. Also, the fish hit really hard and dodge a lot, so absolutely focus your efforts and use all of your abilities early to take down the first fish. After that, one more water mole fight and your at the top of the volcano.
Make sure you grab the Funky Bunch for the Prospector Zeke quest (you can grab it after the fight as well, if you forget) and start the battle. Focus fire Chumba Wumba, the big water mole, and, while you're doing that, make sure you're positioning yourself so you have one crew member near the northwest corner, one near the southwest corner and one near the south east corner. They don't have to be right on them, but make sure they are within one turn's movement away. When Chumba Wumba goes down, he gets back up again (you're never gonna keep him down), so you have to destroy three idols that appear in the 3 corners I mentioned. When you do that, the fight is over, you get a pile of gold as a housing item, 4,000 gold, a new crew member and, once you return to Captain Avery, you reach level 10!