Simply get a chopper (I usualy use the Screamer, anything with missles) and go to where you start the takeover missions and land close to the guy.
As soon as you start the mission, get back in the chopper and use the missles on everything, just don't go too high or it will cancel the mission.
For villages, you can do the same thing, you just have to watch out for the ones with missile launchers.
After the last barricade, just land and take down the flag.