If you want to 100% the game in your first play-through, but don't want a hand-holdy-spoiler-filled guide, then this is for you.

I won't be providing too much depth on how to complete the achievements; there's already plenty of information on that subject. Any details I do provide on how to complete the achievements has been spoilered out for those who want to figure that out for themselves.

What you'll find here is simply checklist of things that should be done by or during certain points in the game, as they can't be completed later. Any achievement not listed here can be completed after defeating the final boss.

• Partial Achievement: Into the Sky
  
  • If you want to unlock all achievements in a single play-through, then you must be playing on Nightmare difficulty.

• Achievement: Sworded Details
  
  • After you've spoken to everyone in Barbado Port (NPCs 1 to 21 in your Notebook), go talk to Slaff in the Militia Headquarters, and he'll give you a free Short Sword.

• Partial Achievement: Hello, My Name Is Adol
  
  • Make sure you talk to Dr. Klaus (NPC 43 in your Notebook).
    
  • Go to the clinic and just as you enter it you'll run into Dr. Klaus. Later in the game you can find him running around town (listen for doors opening and closing), but after a certain point (at least after killing the 3rd boss, but maybe even sooner) he'll disappear for good.
  
  
• Partial Achievement: Forever Level One To Me
  
  • You should buy a mirror from the item shop and save it for later. This doesn't need to be done right away, but should be done before you reach the event below.

• Achievement: Forever Level One To Me
  
  • Push the girl into a monster until she kills it to level her up. Using a Mirror will make this achievement much easier to get, and may even be required.
  
  
• Achievement: Hey Baby, What's Your Width?
  
  • You'll get this achievement while completing the one below.
  
  
• Achievement: I Can't See You, But I Can Feel You
  
  • There's a thin corridor that stretches north and leads to a dead end on the west side of the floor you find the girl on. Push her into it and then equip the Mask of Eyes. With the mask equipped, push her as far back into the corridor as is possible.

• Achievement: Seriously Sworded Details
  
  • Go back to Barbado Port and talk to Slaff in the Militia Headquarters (the NPC who gave you the Short Sword), and he'll give you a free Talwar. You may need to give the Silver Bell back to the Mayor of Zepik Village and escort the girl from the shrine before this can happen.

• Achievement: That Wacky Minstrel
  
  • Go to the clinic in Barbado Port and you should walk in on the doctor and nurse having a conversation with a third NPC. After this happens, go to around where the western Roda tree is and you'll hear some fighting. Find where the fighting is and save the man from the monsters. You may need to talk to Iris in Zepik Village (NPC 70 in your Notebook) before the event in the clinic can occur.
  
  
• Achievement: The Pim's-Lower Approach
  
  • Go to the item merchant in Minea (the one that sells Wings and Mirrors). When either buying or selling an item, get to the point in the conversation where he declares his price, and refuse his offer. Repeat this enough times and he'll give you a better deal.
  
  
• Achievement: Some Kind of Sorcerer
  
  • Buy a mirror from the NPC above and use it near other NPCs. It might be possible to do this later on, as there are NPCs in the tower and one of the chests in the tower does contain a Mirror, but now is the best time to do this.
  
  
• Achievement: Poetry In Motion
  
  • Equip the "Piece of Paper" (which you can find in a chest near the eastern Roda tree) and talk to the girl you gave the Silver Harmonica to, then exit the screen.
  
  
• Partial Achievement: Monster Masher
  
  • Your achievement progress should be at 100/180 before entering the tower.
    
  • Use the Bestiary Potion (found in a chest around where you found the "Piece of Paper") and then kill monsters until all of their fields in your Notebook (HP, STR, DEF, EXP, and GOLD) are filled in. Do this for every enemy you can currently fight (Monsters 1 through 20 in your Notebook).
  
  
• Partial Achievement: Hello, My Name Is Adol
  
  • Your achievement progress should be at 86/88 before entering the tower.
    
  • If you didn't complete "That Wacky Minstrel" then it will be at 85/88, which is acceptable for this achievement, as you'll get a chance to talk to the NPC involved with that achievement in the tower.

• Achievement: Adol the Wall-Crusher Enabler
  
  • Trigger the trap on floor 6 a total of 3 times. It's possible to trigger this trap even after defeating the final boss, but I'm not 100% sure that you'll be put into a new cell (and thus be broken out by Dogi) after that point.