Obtain 15 000 points in the Tashgar mission in the Campaign
This is one of the longer missions, and as such it features a very large number of enemies. If you have been following the strategies from the previous missions and those outlined in Above and beyond the call, then you should not struggle meeting the points goal. Between the gadget stashes and weapon crates, you will be afforded an abundance of grenades and explosives. Put them to good use to help with multi-kills. There are RPGs on the rooftops and in the gadget stashes to help you safely take out the tanks that appear early in the mission.

You can also attempt to execute 10 adrenaline kills (kills while your health is low) and go for the Infiltrator trophy. Each adrenaline kill will add 50 points per kill, so earning Infiltrator during the mission will net you at least 500 additional points toward your goal. If that proves too difficult on Hard, then try it on Easy, as there are still more than enough enemies in the mission to reach 15,000 points without going for adrenaline kills.

Please see Above and beyond the call for point-scoring tips.