LEGO Star Wars The Force Awakens

There are 18 base game chapters (12 main story + 6 new adventures) with 10 minikits each, for a total of 180 minikits. You need to finish all missions on Story first, then mop up in Free Play so you can use the extra characters unlocked from Story.

The TA walkthrough is already a great resource for finding them all, so here it is. LEGO Star Wars: The Force Awakens Walkthrough

If you'd rather use videos for help, here you go, courtesy of Camzillasmom on YouTube. Sorry it's the PS version, but I like her voice and she's funny sometimes. I made links instead of making this page load 18 videos:

Main Story
Prologue - The Battle of Endor video
Chapter 1 - Assault on Jakku video
Chapter 2 - Escape From the Finalizer video
Chapter 3 - Niima Outpost video
Chapter 4 - The Eravana video
Chapter 5 - Maz's Castle video
Chapter 6 - Battle of Takodana video
Chapter 7 - The Resistance video
Chapter 8 - Starkiller Sabotage video
Chapter 9 - Destroy Starkiller Base video
Chapter 10 - The Finale video
Epilogue - Luke's Island video

New Adventures
Poe to the Rescue (D'Qar) (need 10 gold bricks) video
Lor San Tekka's Return (Jakku) (need 20 gold bricks) video
Rathtar Hunting (Twon Ketee) (need 30 gold bricks) video
The Crimson Corsair (Kerroc) (need 40 gold bricks) video
Trouble Over Taul (Taul) (need 50 gold bricks) video
Ottegan Assault (Arthon) (need 60 gold bricks) video
* gold bricks needed are inclusive, so you need 60 total to access all 6 missions *

Yes, there are 30 extra minikits in the 3 DLC missions. They do not count toward this achievement.