By far the easiest place to chase this achievement is Chapter 5: Full House as it has four weapon spawn points on the ground floor, all of which can be quickly checked as you walk into the stage, and three enemies already lined up behind a door upstairs. Enter the stage, check that a brick has spawned, either in the small room below where you enter (2 spawns, one is half concealed by furniture), or in the large room in the top right corner with all the enemies (also 2 spawns). Clear the stage, and take the brick upstairs. Now you have the brick saved in your hand, ready to go, in case you miss the shot and need to restart. Silently kill the enemy in the bathroom, and the two in the hallway and room beyond. Now simply walk up to the door on the right and you'll see one stationary guard and two walking in a circle. Wait until they all cluster together briefly, and throw.
Source:
http://hotlinemiami.wikia.com/wiki/Plain_Luck