You get more Glimmer from killing Majors (Enemies with yellow health bars.) The "Exclusion Zone" Mission on Mars spawns 8 yellow-health enemies, which are usually worth 25 glimmer per kill. Using Resupply Codes gives you even more glimmer for killing them. You load up the mission, open the bunker door, hack the computer, and wait for the alarm to go off. Once the alarm goes off and the door opens, run outside. Ignore the first ship and the Cabal with red health bars. Your goal is the second ship, which flies in when you run past the first few enemies. The second ship will drop off 1 Centurion and 2 Phalanxes, followed by 8 "Imperial Legionnaires" with yellow health bars. These are your targets. Kill all 8 of them, then let the other enemies kill you. Repeat the process, and enjoy bathing in Glimmer. Note: If you kill ALL the enemies in the area, you will hit a checkpoint. That is why it is important to leave a few of the red health enemies alive. I typically leave the Phalanxes (The guys with the big shields) alone, because they are easy to identify, and I am less likely to accidentally kill them. Enjoy!