Star Wars: Battlefront II/Heart of Darkness

Get to the AT-TE
There's not much to this objective, it gives you a yellow objective marker and everything. Just spawn as a grunt or Heavy Trooper and walk to the AT-TE. It takes ten to fifteen seconds to get there on foot.

Kill 6 Acklay
These things are nasty. They can kill you with one swipe of their pincers. So if you chose to use the grunt soldier, find one and start shooting it. Once you hit it a couple times, it will start charging at you. Keep firing! Just back up and keep unloading into its chest or neck. Repeat this procedure for the other 5 Acklay. Of course, if you chose to use the Heavy Trooper, just make sure you hit the Acklay with your rocket. A sure way to do that: switch to your pistol and get the Acklay to run at you. It will always charge at you if you do this, so just wait until you're at a range that you can't miss at and fire a rocket into its chest.

Defend the AT-TE
Your troops can do this pretty much on their own. If you want to switch to another class (the Clone Trooper works best), go ahead, but even the Heavy Trooper's blaster pistol works just fine for this part. You shouldn't have much trouble taking out the few units that attack the AT-TE. Remember to stay close to the walker, but not close enough to get injured by the rockets that hit it. On that note, Assault Droids and Super Battle Droids, with their high-damage rockets, should be your priority targets.

Acquire the power cell
Remember what was mentioned a couple missions back about the word "acquire" in an objective? Well, here it is again. Spawn as Aayla Secura and follow the yellow arrow marking the objective. Don't bother with any enemy units on your way to or from the downed LA-AT gunship, unless your health gets really low because you took too long or took hits (the only way to replenish health as a hero character is to kill enemies). Just pick up the power cell and take it back to your base, again denoted with a yellow marker.

Destroy the CIS defense turrets
Unless you made a big mistake, you should still be playing as Aayla Secura. Look for the six turrets, marked by yellow arrows, and attack them with your regular attack (as opposed to the "throw lightsaber" option). If you died, spawn as an Engineer and hop onto that AT-TE you were defending earlier. If it has taken damage after it was brought online (that was after the fourth objective), repair it with your fusion cutter. Once on the walker, there's nothing that can stop you. You move pretty slow, but the cannons have long range so you don't need to go far. Just get to the large clearing with two Turrets close to you, and you'll be able to get those two and the two atop the hill (the latter with zoom). The others will take a while to get to, but they will fall with only a couple hits from your powerful cannon once you're there. The Separatists also have some Tank Droids in their arsenal, but again your AT-TE will shred them. Once you've destroyed all the turrets, the mission will end.