I have gathered this so far for a little guide:
Begin at Golden Sands and speak to the shipwright, then find Wanda the gunsmith and then find the three clues. (Footprints, Necklace, Note)
Go back to the shipwright and get your new speech options. Now head to Crescent Isle to meet Salty. Now you can begin getting your three journals:
Mermaids Hideaway: Journal is laying next to a campfire
Thieves Haven: On the east beach by a shipwrecked hull
Sunken Grove: Down in the sinkhole on the bench in the biggest cave
Return to Crescent Isle and chat with Salty again. According to the other active thread on this, Wanda's Alchemy Lab is on Wanderer's Refuge in the cave under the big arch.
Again this is just a little more organized as there is an active thread in progress where some guys are being a big help and letting us know the clues.