Im sure by now you have had to deal with the dreaded mini jacks. These are most definitely the most annoying, and deadly enemies in the game. They come in great amounts and swarm you very quickly. A Bomb will only get rid of so many so dont expect that to be your end all solution. What I find works for me is to wait in one of the top or bottom quadrants (not the left or right) shooting as many as I can. When things get a little too close for comfort I shoot a path through one of the lines into the next quadrant. The quadrants I'm talking about are similar to the four spaces made here |X| since they come in forming an X. If you absolutely must, use a bomb to help thin out their numbers.