Star Wars: Battlefront II/Imperial Diplomacy

Capture the Plaza Security Post
Look, you're clad in stormtrooper armor and have a cooler-sounding gun! Don't worry about the transition though; the only changes are cosmetic ones. This mission involves a lot of capturing command posts, so get to capturing that first one. There isn't much cover from your starting location to the Plaza Security Post, but if you advance along with your fellow troopers you won't have much trouble. Once you're on the post, chances are that several Naboo Royal Guards will spawn around you; if this happens, sprint to the nearby health droid and methodically kill them until there's none left.

Capture the Plaza Command Post
This next command post is on the opposite side of the map, and the safest way to get there is by circling around. So backtrack to your starting location and proceed onto the bridge, eliminating opposition as you go. This will take you to a large open dome, from where you can take another bridge that will lead you to the command post. But when you get there, first take out the two turrets to the left with grenades; if left unchecked, some Guard troops will man them and give the rest of Vader's Fist a hard time. Replenish at the nearby ammunition droid, then capture the command post after taking out any opposing forces.

Capture the Guard Security Post
Your commander will smugly inform you that an ITF-T tank has been brought into the battle. Hop onto it, and just advance towards the way it was facing. However, as soon as you turn the corner, you'll come face-to-face with two AAC-1 Hovertanks. These are absolutely deadly in close quarters due to their ability to fire a huge salvo of missiles at once, so drive your tank backwards to exploit the enemy tank's one critical weakness; the missiles can't be aimed, so they'll just go flying erratically at anything over medium range. Your own rockets, on the other hand, only fire two at once but can be aimed precisely. Simply pound away on the two or four (if you take too long, there's a chance two more will appear to assist the first two) tanks from a safe distance until they're all gone.

Then, drive around that corner one more time and eliminate the enemy infantry there by running over them or using your weapons. There's also a turret a little bit further down the way from the command post, so use the rockets to take that out. Hop out of the tank and capture the post.

Destroy the Security Grid Console
There are several ways to do this. If you're good with the regular rifle (or have unlocked the elite one by getting the Frenzy medal), simply climbing the ramp up to where the console is and killing the Guards there will work. If not, you can switch to a Shock Trooper at the command post and set a mine somewhere up that ramp, then try to lure the enemy guards into following you.

But here's the method that's perhaps the most fun; switch to Imperial Officer at the command post, and stand next to the ammunition droid. Now, use your second secondary weapon, the recon droid; climb the ramp with the recon droid, and use the potent blasters on it to kill the guards. If the droid is destroyed, the ammunition droid will have replenished your supply in time for you to try again. If there are only a few guards left, you can try and use the self-destruct function on the droid to take them all out. Note, however, that this does not take out the security console with them.

Whichever method you choose, after the guards are history just go up the ramp yourself and shoot at the console until it's destroyed.

Kill the Jedi Guards
The previous objective will have disabled the particle cannon turrets in the plaza that would have pummeled your troops to death. Get on that tank again if it's still there, and just use the rockets to kill any Jedi you come across (the Jedi can deflect ordinary blaster bolts and even the giant anti-personnel beams operated by the secondary turret on your tank). There are three specific Jedi that you have to kill to complete the objective, and they're all denoted with the big old arrows to assist you. If the tank is destroyed, spawn as a Dark Trooper or Imperial Engineer. The former can use his Arc Caster to injure groups of Jedi at once and render them unable to attack for a few seconds, and the latter has his one-shot kill shotgun.

Kill the Queen before she can escape
This harder than it sounds. The Queen is escorted by a small team of Jedi, and more Jedi spawn all over the map to harass you. The Queen herself carries a powerful beam blaster that will smoke you in seconds, and worst of all, there's a time limit of two minutes to this objective. If you have the tank, this is actually pretty easy, as its rockets take out the Queen in one shot, and can chase Her Highness across the map much more efficiently than on foot. If not, play as a stormtrooper or an Engineer (the Dark Trooper is not tough enough to stand up to the Queen's blaster for long) and focus fire on only her. Finally, if you're really looking for a challenge, spawn as a Scout Trooper and attempt to snipe her from one of the high perches on the map. After all, that is the way the Queen is killed in the ending cinematic.