In this page you can find a detailed description of "Untraceable" achievement that you can unlock in Get Even. You get this trophy for completing a memory without triggering its defense mechanisms.
The best way to get this achievement is to select the first memory in which you play as Red, "Grace_Kidnapping - investigation". There are two factors that support this decision. First, using assimilation on enemies is allowed and it won't block you from getting the trophy. Second, you must deal with only a few bandits. The first enemy is near the starting place (the picture above). Get closer to him while you are sneaking and use assimilation on him. Ignore his friend that goes left and head to the hospital's right building.
Another enemy is in a room on the floor, you can get closer to him by using warp, this moment is presented in the picture. When you get behind the enemy you can use assimilation on him.
Another enemy is shooting from his pistol (the picture above). Approaching him from behind is very easy.
The second to last enemy can cause you the biggest problems because he is patrolling the nearby corridors (the picture above). Wait for him to start moving away from you and try to kill him with a headshot before he can notice you.
The last enemy stands next to the empty chair (the picture above). You can approach him from behind without problems and eliminate by using assimilation. You get the trophy when you interact with the engram and you proceed to the next memory.