There are five Russian hideouts in the game, and they are displayed with a purple eye-symbol on your map. They will appear automatically after making some progress in the story. Go to the southern most hideout, as it is very easy and quick to complete. Once you are inside, web-rush to the ceiling, and you should see the target below (a container with a new suit). Simply defeat the nearby guards, then go to the container to complete the hideout. You must ensure the awareness level (the bar in the top left corner of the screen) remains at zero to get the "Sneaky" achievement. If you raise your awareness level, pause the game, and choose to restart. The hideouts disappear once you have completed them.