LEGO Batman

There are 10 pieces in each level for a total of 300 though the Hero and Villain levels. You can find a written walkthrough here:
http://www.gamefaqs.com/console/xbox360/file/943952/54291
or a collection of Youtube videos here:
http://www.xbox360achievements.org/forum/showthread.php?t=95...
to locate them all.

This achievement is for get all the collectibles. There on ten on each story mission and there are 30 story missions for a total of 300 memorabilia.

-First play through all of the missions collecting as many studs as possible. (You will need these to purchase the Mini-kit Detector you unlock after finding it's Red Brick)

-You will also need certain characters to reach places that were inaccessible during the regular story mode.

-Play through every level in Free Play collecting all those Mini-kits until you have all of them (You can check how many you need in every mission by selecting it)

Note: The mission Arctic World (Vilians Ep.2 Chapter 5) has an ice slide that makes one of the mini-kit near impossible to get.

-There are 2 ways to get it;
#1 when you get to the ice slide immediately go to the right side go through the two little "flags" and then change to the other character and lean left to go through the remaining three "flags" and there you go.
#2 Have two people play where one goes to the right and the other to the left and presto mini-kit.

One part of this solution on the Villains Chapter 3, Part 2 - Biplane Blast had me flying around for almost half an hour before I figured it out. So even though it's late in the game's life if anyone is just clearing it out of their backlog like me here's the solution. There are 3 Joker signs you have to flip. They are purple with the red and green push panels like earlier in the game. So like earlier in the game I was aiming at the green piece to push the sign. It wasn't until in frustration I switched to trying to destroy the sign that I figured out the first part. Don't aim at the green, aim directly at the sign. You'll know you're doing it correctly if the bullets are bouncing off of the sign. Keep doing that (you might need to make a few spins) until the sign flips. I flipped all three and the canisters in front of them still didn't pop up. So I thought maybe I have to destroy them now so I started shooting at them again, after a little while the first sign I was shooting at flipped just a tiny bit more and when I went to the other two they did the same. Then finally the canisters popped up and I was able to destroy them and get the mini-kit. Hope this helps anyone who might be stuck like I was.

Note: Due to the character limit in the descriptions, timestamps for every minikit couldn't be listed in the video above. With that in mind there's a playlist for each episode here that does: https://youtube.com/playlist?list=PLfgTQqTID19EuP6Eh4Dzmded_...