At first glance through the levels you may not see things that can help. For example, there are many pipes that let you climb on. If you hide up there and the guards in the black do not see you, move along the pipe and they will not shot you. You can also hide behind items that appear to be up along the wall (lockers, plants, curtains, plants boxes, and other items). However, if one of the guards sees you go behind them to hide, he will hit the alarm more then once. Normally if you hide long enough the alarm will stop. Also if the guards in the level stop and hit the alarm and see you, run behind something. If the guard stands there, you are in trouble; when the guards that are in black see the other guard, they will stop and throw bombs to flush you out.