Aliens need to secure the lift room or dark staircase ASAP. Although the lift room is a good spot, jetpackers can get in and seriously harass you with nades once SD hits. The dark staircase's only downfall is the OM will block tyrants, other than that it is the best location. The OM goes on the lowest landing, an egg or two under the stairs, and the rest of the bps on tubes. They also need to secure the catwalk above human default base.