Crackdown 2

During the first "mission" of the game, you will see 3 blue/grey circles on the mini-map. These represent the Absorption Units. Go to the markers and prepare for a firefight. After clearing out the few Cell members step on one of the blue pads surrounding the device and wait a few moments. The device will activate and the achievement will be yours.

This really couldn't be that much easier. Locate the AU on the map, run up to it killing any nearby resistance (there's normally a couple to half a dozen Cel operatives on the platform with the AU) and stand on one of the four switch on the platform until the AU is fully configured (there's a meter in the top right corner of your HUD.)

Like the beacons, you don't have to worry about causing any damage to the AU, so if you want to go in with explosive weaponry, go for it...

It might be easier to clear out the Cel strongholds in the region first as there's at least one that can be quite risky (lots of grenade launchers and homing missiles), but then if you're wanting an easier life of it, I'd recommend clearing all the Cel strongholds before doing any of the rest of the work anyway!