So this isn't so much a guide as it is advice where to find a good guide. I'm only posting this since there is nothing here, and the first guide I followed didn't get the achievement to pop.
As I've played through the remastered versions of FF7, FF8, and FF9, I've found myself using the guides at jegged.com for them on each game. They are pretty easy to navigate for achievement hunting, even though the guides are written for the game and not achievements. Anyways, if you are like me and were using that guide for Obel Lake, the achievement won't pop until you pick up BOTH the Three Stars item and the Luck-J Scroll. True Achievements has a Steam site that has a wonderful guide there to follow, which I will link below. All credit to the author - DarkDan88
TrueSteamAchievements