For Liquid Armor guys, keep doing the beginning of Western Europe on Normal. There will ALWAYS be one at the area after the first gate.
For Electric Armor guys, keep doing the first two areas of New England on Hard. This may be a bit difficult, but make good use of apps and it should be easy enough. Each time you do this, you will get 3 electric kills.
I have moved to PC gaming, so I
won't be on Xbox LIVE anymore.