In order not to die in the first few levels, you will need to understand the basic principle of survival on this earth, that is, that you do not stand still. Always run forward and go to shoot from the enemies you come across on the way. So sometimes you can just avoid them. But do not forget about the number of cartridges in your cage, always collect ammunition. Also it is worth remembering and about first aid kits, which are also you will find the level.