Of all the scenarios that involve bashing in your opponents face, this is in my top two. Firefight is not only about blasting your opponent off the table, but you also want to load up on guns in the Panoplies, kill their Lieutenant(s), kill their DataTracker, kill their Specialists, and meanwhile you've got two Classified Objectives to worry about. Just to make life easier, there are 16" deployment zones and AD troops get a cumulative +3 bonus to land on the table. So how do you manage surviving this chaos? Lets find out.
First off, lets talk about deployment and the table set up. Instead of the standard 12" deployment zones, Firefight has 16" zones, giving you an extra 4". This also means units with Forward Deploy L1 will be deploying 20" up the board, L2 will be up to the half-way mark, furthermore, it means your HVT will have to be 20" from your own table edge. Since there are two classified cards in use this scenario, it is very important that you don't stick your HVT somewhere that your opponent can easily get those points. That extra distance can also be helpful defensively, if you start further back in your zone, enemy infiltrators and impersonators will have a more difficult time getting to you. Don't feel obligated to deploy all the way up to your edge, especially if you are playing against Combined, Haqq, JSA, or any sneaky opponent you may suspect of using impersonators or superior infiltration.
Down the middle of the board, there are 3 Panoplies, which any model can interact with, not only specialists, though specialists do get a bonus (roll twice on booty and pick the result). While it is nice to open up the boxes and get some awesome weapons, remember that you only score 1 point for getting more weapons, so don't feel too concerned about controlling them during the game, but instead go for them when the opportunity is good.
There are 4 different ways to score points in this scenario, all revolving around killing enemy models: Specialists, Lieutenants, DataTracker, as well as killing more army points. Infiltrators, fast units, AD troops, linked teams and TAGs all excel in this capacity. AD troops in particular are going to get +3 to land, which does stack with hacking, or the EVO bonus, and they're even allowed to deploy in the enemy deployment zone. I cannot emphasize that last point enough, it basically makes anyone with AD into Van Zant... this scenario is one of the few times that you could easily justify several AD units.
When it comes to tracking score for the match, just killing more army points isn't enough, since it doesn't stop your opponent from scoring the other 7 points. I personally would aim to have a variety of specialists available to do the Classified Objectives, then make it a point to kill the obvious targets: Specialists and the DataTracker. Lastly, be on the look out for obvious lieutenants, this scenario doesn't use Retreat!, but your enemy can still suffer loss of Lieutenant. A linked Alguacil with combi rifle that isn't a specialist should be a high priority targets for your AD units walking in the enemy backfield.