The Strength of Brothers
Eliminate Sun Fac
After you start this level, you'll automatically meet up with Delta 07 ("Sev"), your designated sniper. Sun Fac is in the room beyond his location, so shoot the glass and move after him. He'll start running, of course, after seeing the badasses that are on his tail, and you can't do much to catch him at the moment, so don't feel compelled to run after him. Just take it slowly and clear out the first room before approaching the door beyond.
Unfortunately, the second room here features not one but two Super Battle Droids. Luckily, you can take the one by the door on first, so command your team to target their fire on it with your use key so that everyone is aiming at it at once. You should also have EC grenades by now--if not, there's a box by the door--and you can use these to temporarily stun to SBD's, allowing you to take their health down much more rapidly. Eliminate both of them before healing up and placing a charge on the door inside the room.
Sun Fac is in the room beyond, but he'll quickly bring up a shielded door on the path leading to his landing dock, preventing you from following him to his ship. Luckily for you, there's a balcony above the docking bay, where you'll be able to set up Sev in sniping position; if you give him enough cover, he'll snipe away at Fac's ship until it explodes, finishing off your first major objective on Geonosis. Shortly thereafter, a strange ship can be seen blasting off from the planet. Hmm....
When you're ready to move on, find the elevator leading down further into the planet's interior. It appears that there's a droid factory under the surface that's continually spitting out reinforcements to the battle topside; your mission is to shut it down.
Infiltrate The Droid Factory
Locate Jamming Device
Unfortunately, your communications with Advisor are being jammed by some kind of interference device within the droid factory; your first task here is to find it and destroy it. Luckily for you, you're going to get your first weapons upgrade shortly after you begin the level, in the form of a sniper rifle attachment for your blaster rifle. With it, you can snipe away at any distant enemies with much greater accuracy than your normal blaster. Why this was hidden away in an underground droid factory rather than given to you at the outset of your mission is a mystery to us, though.
Immediately after you breach the first door and proceed through the corridor beyond, use the sniper rifle to destroy the explosive barrel on the bridge across the chasm; this will destroy the bridge and most of the Geonosians on it. From there, start heading down into the Geonosian birthing chamber. You'll note that there's a sniping position near the entrance to the egg chamber; set up Sev there and place the other troopers on guard duty nearby. Most of the eggs here have baby Geonosians inside of them, which will spit acid at you when they hatch, so switch over to your sidearm weapon and start blasting them from the distance; you can also shoot the barrels to blow multiple eggs at once. Sev will be able to easily hit the Geos after they hatch, making your path through the chamber that much easier.
Disable Jamming Device Shield
After you actually find the jamming device, you'll have to destroy it, but unfortunately for you, it's shielded, so you'll first have to destroy the shield before you can destroy the device itself. A twisted web, indeed! Unfortunately, there are a couple of spots from which Geonosians will be infinitely flowing in this room, so you'll need to keep a tight leash on your group in order to complete your objective.
To begin with, have one of your soldiers take up a position at the grenadier spot above the jamming device, then order the remainders of your squad to take up a position near him. When they're all stationary, help them kill off any remaining battle droids in the area before cancelling their orders and forming them up on your position, then move around the large rock to your right.
The console control for the shield that protects the jamming device is on a ledge at the far end of this room, so quickly skirt the right side until you spot a pair of sniping locations where you can position two of your squadmates. You'll want to get here fast, because you will have passed a spot that triggers the spawning of bugs; getting the snipers in place will let you take them down from long range. When they're set up, take the remaining teammate and head towards the console. Use the last teammate to slice said console while you watch his back. When the shield comes down, return to your snipers and prepare for the assault on the jamming device itself.
Destroy Jamming Device
Now that the shield has come down, you'll notice that a new sniping spot has appeared directly across from the charge-laying spot for the jamming device. This is where you want to group your soldiers up for the next little phase of the battle here.
As soon as you order someone to lay a charge on the jammer, a horde of droids and bugs will spawn in, so what you really want to do here is tell all of your soldiers to form up behind the sniping spot (with one of them actually manning it), then command one of your soldiers to lay a charge; when he gets close enough to cause the enemies to spawn in, though, cancel the order and draw him back to your position, then kill all of the enemies until the room is completely clear. It'll take a minute or two to do so, but will allow your squadmate to lay the charge unmolested, since he won't have any enemies on his tail. You can also just attempt to lay the charge while your squad is still taking fire, of course, but you'll have to be sure that none of the bugs can whack your squadmate while he's placing the explosives.