The object of this mission is to hop Tanya from one island to the other, freeing prisoners as you go along. If you shoot them personally, Tanya can kill legions of enemy soldiers. But if you look away for even a second, you'll be scraping her ponytail off the ground. Weighing the choice between saving prisoners and killing soldiers is what this mission is all about.
Your first stop is the island to the north. After you kill the soldiers, load Tanya and the prisoners into the water transport. All but one - leave that soldier up by the crate. The crate will heal all your units back to full health, but you should save it for a rainy day.
When Tanya hits the second island, your friends will send a transport chopper to make your island-hopping easier. No sooner does it land, however, then a pack of MiG fighters try to blow it up. The very instant the chopper touches down, select it and move it away. The fighters' rockets will impact harmlessly on the surface. There's a healing crate on this island also. Again, leave someone who can pick it up in an emergency.
The enemy attack helicopters are big, noisy nuisances. The moment your reinforcements touch down, the enemy choppers cut them to pieces. The solution is to load the rocket infantry into the transport helicopter, then shove Tanya in after them. Tanya kills the soldiers, and the rocket infantry kill the enemy attack choppers.
Don't let any of your rocket infantry die! You need every one of them for later. As they stand before the gates of death, pick up one of the heal crates you left behind. Viola! What a miraculous recovery! Enemy subs dot the waters, and your gunboats will take a beating unless you kill the subs with the "shoot while moving" technique.
When you arrive at the northeast island, send your spy along with Tanya. Breach a hole in the wall with your rocket infantry and send Tanya and the spy through to the radar dome. Infiltrate the dome with your spy to muck things up for the bad guys.
The northwest island seems impenetrable, but it isn't. When your tanks arrive, run over the enemy soldiers, but don't venture too far to the north or west. Otherwise, the Tesla coils will rip them apart. Your destroyers have an advantage of range, though, so you can safely shoot at the Tesla coils from the water. All you have to do to finish the mission is land the rest of your troops on the shore and destroy the tech center.