-If you get one of your commandos into the prison, the prison will explode and your commander will still be standing there. After that, take him to the northeast village and avoid the GHOST troops.
-When trying to save Hooper from prison, take two Commandos, one Tank, one Mobile Artillery, and two Bazookas. Send the rest to the outpost by the right slope to get on top of the hill. Wait until they start blowing it up, then take the remaining men you held and go to the base. Blow up the prison with Commandos. There will be no men or machine gun bunkers. After that, send him to the flag at the northeast village. Do not worry -- there will be one or two men, but Hooper is strong and will make it without fighting.
Create structures that make units (Barracks, V. Factories, etc.), then have each of them to make units. For example, if you made two Barracks and told one to make fifteen soldiers and the other to make fifteen soldiers, both barracks will make them. This works for both IPC and GHOST. This trick will allow you to make soldiers and attack a much faster.
The best map is Sardines as you can build more on there. A good strategy is to build all the newest things that comes out. However, this will require tons of money, and some of the new things you unlock are useless. For example, the planes, spies, commandos, subs, boats, advanced things, doctors, civilian helicopters, and grenadiers.