My Achievement Suggestion is:
Crafting:
Beginer Blacksmith: Have crafted all of the Pré - HardMode Armor;
Magician Taylor: Craft Every Type of
Robe;
Darkness Arrival: Craft a Night's Edge;
With the Power! (or Force idk! 
): Craft a (Blue, Green)
Phaseblade; (This will be a hidden achievement!,)
The Dark-Side: Craft a (Red)
Phasesaber; (This will be a hidden achievement!)
The Chosen One: Craft a
True Excalibur;
Darkness Fury: Craft a
True Night's Edge;
Total Annihilation: Craft a
Terra Blade;
The Dragonfly Cutter: Craft a
Tonbogiri;
Circle of Light: Craft 5
Light Disc's;
Yin-Yang Balance : Craft a
Dao of Pow;
Destructive Megalodon: Craft a
Megashark;
The Desert Rule: Craft a
Sand Gun;
Starfall: Craft a
Stafury;
Apprendice Magician: Craft all of
Gem Staves;
Experienced Magician: Craft all of the Craftables Hard-Mode Spells;
Alchemist: Craft all potions;
Ready for Combat!: Craft all of consumible thrown-weapons;
Colorfull Masterpiece: Craft all dyes;
---Hard Ones---
Legendary Blacksmith: Have crafted all Armor;
Collecting:
Armor Collector: Colect all of non craftable Armor;
Vast Resource: Collect every potion ingredient;
Biologist: Capture all of the animals of the game;
Astute Fisherman: Collect every bait on the game;
Key of Kingdom: Collect the
Keybrand;
Christimas Gift: Collect the
Christimas Tree Sword, Fruitcake Chakram, Chain Gun;
The Hollow Sword: Collect the
Horseman's Blade;
The Sealed Sword in the Stone: Collect the
Enchanted Sword;
Halloween Bullet: Collect the
Jack 'o Lantern Laucher;
The Power of Money: Collect the
Coin Gun;
Haunted Artillery: Collect the
Stake Launcher;
Bloody Massacre: Collect
Bloody Machete;
Vampire Killer: Collect the
Vampire Knives;
The Justice Strike: Collect the
Paladin's Hammer;
Librarian: Collect the Spells:
Golden Shower, Magnet Sphere, Cursed Flames, Cristal Storm, Demon Scythe, Book of Bones and Water Bolt;
Ice Queen or Ice King: Collect the
Blizzard Staff;
Save The Queen: Collect the
Queen Statue;
Protect The King: Collect the
King Statue;
Throphies Hunter: Collect all of the Pre HardMode Thropies;
Throphies Maniac: Collect all of the Hard-Mode Boss Thropies;
---Hard Ones---
The Wise Wizard: Collect all of the Spells on the game;
The Mighty Hero: Collect all of the Melee weapons on the game;
The Wandering Archer: Collect all of Thrown-Weapons on the game (Bow, Bowguns, Guns, and Thrown);
Garden of Stone: Collect every Statue on the Game;
In Game:
Mayor: Have all of NPC's;
Treasure Deposit: Have all types of Chests;
Costume Contest: Have all of Halloween and Christimas Costumes;
The Hero: Have the Hero Outfit;
Treasure Hunter: Have the Archelogist Outfit;
Elegant Outfit: Have the Tuxedo Outfit;
Virus Erradication: Kill 1000 Zombies;
Rainbow Blobs: Kill Every tipe of Slime;
Master of Disguise: Defeat a
Mimic ,
Frost Mimic;
What a He..!???: Defeat a
Lost Girl;
The Witch Hunt: Defeat a Tim;
Giant Gelatin: Defeat
King Slime;
Cold Heart: Defeat the
Ice Golem;
Follow Wind: Defeat the
Wyvern;
Loyal Guardian: Defeat the
Paladin;
Spirit Tree: Defeat the
Mourning Wood;
Possesed Tree: Defeat the
Everscream;
Lurking in the Dark: Defeat the
Eye of Cthulhu;
Shadow Destruction: Defeat the
Eater of Worlds;
Bloody Decomposition: Defeat the
Brain of Cthulhu;
The Guard of Mausoleum: Defeat the
Skeletron;
The Thing grow Serious: Defeat the
Wall of Flesh (Enter in the HardMode);
Recycle: Defeat:
The Twins, The Destroyer and
Skeletron Prime;
Deathly Scent: Defeat the
Plantera;
Forbidden Altar: Defeat the
Golem;
The King of Ocean: Defeat the
Duke Fishron;
Strange Night: Survive a Blood Moon;
Halloween Spirit: Survive a Pumpking Moon;
The Night of Naughty: Survive a Frost Moon;
Apocalypse: Survive a Solar Eclipse;
Invasion of Faraway Lands: Survive a Goblin Invasion;
Criminal Hunter: Survive a Pirate Invasion;
-
--Hard Ones---
Vanity Especialist: Have all of Outfits;
Biomes:
A Light in the Dark: Discover a Glowing Mushroom Biome;
Sealed Dungeon: Discover a Pyramid;
Flying Paradise: Discover a Flying Island;
Silk Grotto: Discover a Spider's Nest biome;
I'll suggest more, like some challenges like time flying, speed runs and other things!
