Construction Yard- The Construction Yard is the most important building you can get. Without it, you canít construct other buildings, and are thus limited to your current buildings. Protect it at all costs. These are good targets for Saboteurs and Engineers. Death Hand Missiles and Ornithopter Strikes pose a threat too. You can usually deploy your initial MCV where ever it is sitting. But you might feel the urge to scout around your island first. Let me remind you that MCVís are as slow as Devastators and make poor scouts. You are best advised to deploy it where it stands and sort out the details later. As for the upgrade, get it as soon as you can so you can make the bigger Concrete slabs. Construction Yards are made from deploying MCVís. They cannot be constructed otherwise. Construction Yards cover a 3x3 foundation.
Concrete- Concrete comes in two sizes: 2x2 and 3x3. You can only make 2x2 initially. But by upgrading the Construction Yard, you can also make 3x3 foundations. You might notice that most structures have a space in front of them where units come out. The building isnít actually on those plates. Capitalize on those buildings! If you want to make a Wind Trap, only make a 2x2 foundation. Make sure the top four squares of the Wind Trap are on Concrete, and it will function properly without taking erosion damage. Sure it only saves you a couple bucks. But later you might be pressed for cash, so youíll have to cut corners where ever you can. 2x2 Concrete requires a Construction Yard. 3x3 Concrete requires an Advanced Construction Yard.
Wind Trap- Since your base wonít function without these, there is no point in my telling you not to build them. In fact, build them in excess. Whenever you are two or three blocks away on your energy bar from shutting down, build a Wind Trap. Wind Traps donít take much of a beating to put out of operation. These are good targets, because they slow down your enemies war-machine. However, you must also protect your own. It is not a good situation to be without power. Wind Traps require a Construction Yard. Wind Traps cover a 2x3 foundation.
Wall- Walls are a cheap way of defending your base. As was said before, after getting two or three Harvesters each with their own Carryall, Wall-in your Refineries. Other structures that are good to Wall-in (if possible) are Construction Yards, Silo bunches, and Turrets. This keeps them safe during a siege or eliminates the possibility of them falling prey to Saboteurs or Engineers. Walls require a Wind Trap. Walls cover 1 foundation square.
Refinery- This is another must-have structure, since you need these to bring in cash. Protect them from Saboteurs/Engineers. Likewise, they make good targets for your own special units, or for attacks in general. A Refinery will hold about 1200 Solaris before you need to make Silos. Also with each Refinery you get a Harvester. Refineries require a Wind Trap. Refineries cover a 3x3 foundation.
Barracks- Infantry are your first combat units. They are also cheap to make and easy to mass produce. It is a good idea to make a Barracks a first priority after getting your Refinery up and running. Sometimes a second Barracks to speed up training is a good idea if you think infantry will decide the game. Upgrading the Barracks is a must because it allows Troopers and Engineers, and Thumpers in multiplayer games. Barracks require a Wind Trap. Barracks cover a 2x3 foundation.
Silo- Eventually your Refinery is going to run out of storage space. This is where Silos come in. Each Silo holds about 600 Solaris before running out of room. And since they are only one square big, you can bunch them up and Wall them in. They make good targets because they hold your enemies cash. Capture them if you can, but if that doesnít work out, destroy them. Silos require a Refinery. Silos cover 1 foundation square.
Light Factory- The Light Factory allows access to the Trikes/Raiders and, when upgraded, Quads. It is usually good to get one early in the game. But if you would rather scout out the map later, you can wait. The only real reason to get a Light Factory is Trikes/Raiders for scouting purposes. But in the late-game, Quads come in handy as a quick substitute for Combat Tanks. The upgrade is recommended, but you donít need it until the real fighting begins. Light Factories require a Refinery. Light Factories cover a 3x3 foundation.
Gun Turret- The Gun Turret is the basic base defense structure. With the attack capability of a Combat Tank with stronger armor, the Gun Turret is usually a solid choice for defending your settlement. But donít rely on them too much, since they have a problem taking on masses of infantry, especially Troopers. Gun Turrets require a Barracks. Gun Turrets cover 1 foundation square.
Heavy Factory- This structure along with the Outpost form the real important links in the tech tree. These two structures allow access to many more structures and units. The Heavy Factory will be the most important unit producing building when the real fighting starts. Upgrading it is a must, since the only combat vehicle allowed initially is the Combat Tank. Upgrading also opens more options. Heavy Factories require a Refinery. Heavy Factories cover a 3x3 foundation with an extra square at the top.
Outpost- The Outpost is the second major structure, the other being the Heavy Factory. It also gives you access to the mini-map, allowing you to better survey the battle. However the Outpost requires a good amount of energy. You should have at least two Wind Traps when you get this structure, but having three or four will be even better. Outposts require a Barracks. Outposts cover a 3x3 foundation.
Starport- The Starport is a dead-end structure. It doesnít add new units, unless your Ordos since it allows you to purchase Missile Tanks. Get a Starport if you are in dire need of replacement units during a large attack. Since all the units come at once, you donít need to worry about individual units getting taken out the second they appear. Units bought through the Starport are a bit more expensive however, and usually takes a little longer to receive the units than if you were producing them. You can usually skip this structure to save on cash. Starports require a Heavy Factory and an Outpost. Starports cover a 3x3 foundation.
Repair Pad- Though only required if you plan on getting MCVís, the Repair Pad is a good choice to have in a prolonged war. But if you are fond of suicidal attacks, the Repair Pad is a waste of cash. This is another structure you can skip over to save cash. Repair Pads require an Advanced Heavy Factory. Repair Pads cover a 3x3 foundation.
Rocket Turret- The Rocket Turret is the preferred form of base defense. It has a stronger attack that can usually cause a lot of damage on slow moving targets or stationary attackers. Even infantry are good targets. Moving targets are a little tougher to attack. A Rocket Turret and a Gun Turret side-by-side is a good defense, especially if you Wall them in. Rocket Turrets require an Outpost and an Advanced Construction Yard. Rocket Turrets cover 1 foundation square.
High Tech Factory- Allowing the Ornithopter Strike and Carryalls is this buildings ability. It is a must-have to raise a good stock of resources, since Carryalls double the speed at which you harvest and refine spice. You must upgrade this building to get the Ornithopter Strike. High Tech Factories require an Outpost. High Tech Factories cover a 3x3 foundation with an extra square at the top.
Ix Research Center- This is the last must-have building. It allows the Sonic Tank, Devastator, and Deviator. It also allows the construction of the Palace. Ix Research Centers require an Advanced Heavy Factory and an Outpost. Ix Research Centers cover a 3x3 foundation with an extra square at the top.
Palace- The final building available is the Palace. The Fremen, Saboteur, and Death Hand Missile are made available at this site. The Harkonnen benefit the most from the Palace, while the Atreides benefit the least. Palaces require an Ix Research Center. Palaces cover a 3x3 foundation.