To get this achievement, you need to draw attention to yourself and make guards hostile. Kill a few people or get the attention of some guards so that they are hostile. At that point, you need to find a place to hide to avoid detection.
One of the best methods is on King of Chinatown. Find the alley that leads to the drug dealers appartment. When you've found it, kill the cop at the end and then start shooting into the crowd until the cops come after you. Run down the hallway, kill the dealer and then climb into his closet. If none of the cops have seen you then you just have to wait until the message "Clear" pops up on your screen. At this point, the achievement should unlock.
