Crackdown 2

If you want to make life that bit easier for yourself, go for this achievement first...

Run round the city wiping out each and every Cel stronghold... thus cutting down the number of enemies you'll run into when you go chasing after the other objectives like Freak breaches and Absorption Units and Beacons...

To secure a tactical location/Cel stronghold, locate it on the map, head to the location, and hit the 'back' button to call in the helicopter backup... You'll be told that there's too many Cel in the area and a meter will appear in the top right of your HUD so you can see how many you have to kill before your reinforcements will arrive. On your radar, you'll see all the relevant Cel operatives. Ordinary Cel members won't count towards clearing a stronghold - only the ones on your radar.

There were three strongholds that I found a little more difficult... One atop the buildings just east of the fairground - a lot of grenade launchers meant that you were being picked up quite quickly and juggled for a while... another tricky one was in Unity Heights - mostly down to the raw firepower they were laying down (a lot of heavily armoured guys wielding turret launchers and gatling guns, and a lot of other explosives toting Cel guys)... and the trickiest one was at the plaza in Unity Heights, partly because I'd cleared out all the surrounding Cel and was only a fraction down the meter, though I could see plenty of them on the radar... Hint... They're all high above you! Not sure if there was an easy way to climb up to the level where they were, but I went and picked up a helicopter from the agency tower and once I'd cleared out the guys on ground level, just flew up and toasted the rest of them from the safety of my helicopter!

Hirsute Dave points out the rocket boots from the Toy Box DLC will help out greatly with this... Great advice, and thanks for reminding me about that (don't think I had the DLC when I wrote the solution initially!)... They also help out with doing the wingsuit missions as well....

Note that some of the locations are linked, and if you don't complete all the linked locations quickly enough, Cel will overrun the ones you've already completed and you'll have to do them again!

For what will most likely be your final TL the huge tower. There are white lights around the side of the tower that are scalable, this seems to be the only way to climb the tower. Also these lights are quite unreliable. So be persistent because it can be frustrating.

To get this you have to clear out every red Cell marker in the city. The first two islands shouldn't be too difficult but the third island can be a real pain. I recommend doing all the third island tactical locations with at least one other person in order to increase the odds of survival. If you do go it alone just remember to RUN if your health is low. Go find cover and wait for your health to charge up. The last few locations are chock full of rocket and sniper guys so keep that in mind.

Here is a possible way to climb of the large Tower Unity Heights to do this Tactical Location. This Video is not from me, but it helps me a lot.

Sorry for the bad Quality!