Estate

Compound

No sense in going quiet at the outset here; bring down a machinegun from the chopper, like the excellent 21E, and start going to town. You're going to die a couple times before reaching the first checkpoint, but you can improve your odds by staying behind cover at all times and using smart positioning of your team. Move them in front of you and be sure that they're behind cover and facing whatever route you're about to take.

After getting to and cutting the power, a door will be unlocked along the path you just took. Backtrack to find it and head through.

Hacienda

After refitting, switch to silent mode for your team and equip a silencer. Snakecam the door and wait for the drivers to move off into their positions, then sneak out the door and start headshotting them from a distance. No need to get a sniper rifle here; an assault rifle with a silencer should have distance enough to kill these guys.

Stealthily make your way across the garage area until you reach the stairs leading up to the residence itself. There are plenty of tangos inside, so it's probably wise to switch back over to your machinegun and go in guns blazing. Enter through the first door you spot and start clearing out the entire place, pausing after every firefight to see if more soldiers don't drop through the skylights. After a while, there'll be a welcome surprise in the form of more Rainbow Six squads that will appear to help out.

Head upstairs and switch back to silent mode, if you like. After clearing out the first few enemies, though, start snaking doors; one of them will have two shielded enemies behind it. Switch back to assault and breach that door to kill them both.

Eventually you'll reach a room with a computer and a bomb in it. As you might be able to tell, this is going to be a tricky situation. You'll certainly want to have a machinegun here. After telling your teammates to hack the computer and disarm the bomb, the bomb will eventually explode, dropping one of your teammates. Tell the other one to patch him up, then get your machinegun ready. Stand underneath the overhanging ceiling and start firing away at the enemies as they drop from the railings and the windows. There are going to be around eight of them all told, with more on the upper level, so as soon as your teammates are fit, bring them back underneath the overhang themselves. If you're having troubles, backtrack to a refit station and use smoke grenades to obscure the area a bit before the bomb goes off.

Showdown

You'll somewhat foolishly leave your teammates behind at this point and head after Nowak on your own. Be sure that you have a machinegun in your hands as you head out the door here; you'll also want to pick up grenades and incendiaries from the refit boxes. As you leave, you'll get the balcony exploded underneath you. When you get back on your feet, immediately duck behind one of the low walls in front of you.

The assault chopper here is going to be pretty annoying, for obvious reasons; it'll kill you rather quickly if it catches you out of cover. At the outset, focus on the small shed off to your left. Kill the enemy that pops out of there, then look to the right and kill the soldier that rappels down from the roof. With that done, your conversation with Joanna should be about done, allowing you to periodically pop over your cover and fire away at the helicopter. You can attempt to blind fire, but you'll probably miss it due to its distance from you.

After a goodly amount of fire (be sure to duck down as you take damage), you'll get confirmation that the chopper is calling for help. When this occurs, it'll fire missiles at you. You'll have to stand up and run away from your cover in order to avoid getting killed here. When the missiles have impacted, work your way around the corner and hide behind the other low walls near the tennis court. You don't need to worry about the chopper at this point. Instead, focus your fire on the soldiers that come out of the shed and attempt to kill them before they reach the tennis court. If they do get close to you, they'll often throw grenades, and there isn't much room between you and the wall behind you, making these lethal more often than not. You're going to get your fair share of cheap deaths here, but if you shoot the enemies as they come out of the building, you'll hopefully be able to prevent them from chucking their deathballs. No need to fire on the chopper during this section of the fight. Eventually, however, it will fire more missiles, so retreat into a corner of the area and get away from your cover.

When the second salvo of missiles lands, you're almost home free. Dash across the tennis court and into the shed, using its windows as cover while you fire on the truly endless stream of enemies here. All you have to do now is survive. Throw your grenades and incendiaries into the tennis court to take out some of the enemies, and use your machinegun to finish off the rest.

After the chopper goes down, the wall of the shed will collapse, leaving you to face Gabriel one-on-one. Wait for him to raise his gun, then blast him in the head to finish him off. Hooray!