When you start, run as far as you can on the map to the right. Once you get far enough, there is an overhang which protects you from most enemy fire (except from fire on the far right). Run under the overhang. Press [Down] just as you hit the wall of the overhang. You will be brought into a place where you cannot get hit. To remain there you must release [Left] before [Down]. From here you can do a few things. You can you can remain hidden and get down quickly by releasing [Down] before [Left]; stand up by releasing [Left] before [Down]; get above the overhang by pressing [Down] once standing up; go further into the overhang by pressing [Right]; get down by pressing [Left]; or spaz out by pressing [Up].