At the 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 number of 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.