If you want to get far in the game, you'll have to make the most of a precious resource: Celenium. Early on, the easiest way to acquire this is by earning achievements, which reward you with small piles of Celenium. Over time, that can stack up and allow you to invest in builders that will allow your base to function much more efficiently (you should mostly ignore other potential uses for your Celenium). You can sometimes also find Celenium by destroying rocks and trees, so always be on the lookout.
Defense
Defend your base with upgraded units. Surround your base with barriers in order to make it difficult to penetrate. Placement of defensive structures is important, as well as upgrading defensive towers. Strengthen your base starting with the most important structures. Focus on the Command Center (if you care about Ranking points) and resource buildings. Place silos and resource producing buildings behind walls, together with all the defensive buildings available. Leave the Command Center outside to enter quickly in protection mode after a player takes it out for points (and thus protecting your resources). Leave space between defensive walls and your structures. Attacking troops will usually take time to take out the wall and not shoot over it. Place all non-essential buildings (Research Lab, Barracks, etc) outside your main area to serve as decoys. Leave spaces between them to spread out the base layout as much as possible to force enemies to take more time to take out all your structures.
Heroes
Heroes are unlocked as you progress and increase your Command Center levels. Heroes have elevated stats and have unique skills that can be used in battle. You must spend skill points to activate those skills. Once a skill has been used, the subsequent use of that skill during the same battle will require a higher expenditure of skill points. You can control the movement and target that your Hero attacks.
Offense
After getting a decent amount of resources, begin building your arsenal by maximizing your Deployment Yards and increasing their upgrade level. This will boost the total number of troops you can deploy each time you attack an opponent. Use the Ballistics Lab to upgrade your human troops, which can boost those who undergo training. Later, you can extend your forces by using big vehicles and aircraft. Do not rely on single type of unit. Each unit type has a purpose; use them to your advantage. Each unit has their own advantage and disadvantage. Develop a strategy that can minimize the disadvantages by mixing different types of units in battle. Only have a few Juggernauts and have the rest or your troops as Snipers. Send in the Juggernauts first to draw enemy fire, then use the faster Snipers to get resources. This method is better for resource collection rather than earning stars. Intentionally keep your ranking low by losing when needed if you are interested in resources. Do this by sending in a single troop into battle then retreat to lose the fight. You will get a ranking penalty, which will give you more easily accessible bases to farm resources. Always send in as few troops as needed to win in order to maximize profits and to allow you to attack frequently. Do not use your Hero's special abilities; they are a waste of points if you are only interested in resources. If you want to increase your ranking instead of collecting resources, upgrade your troops to their maximum levels. Only send in the best possible ones. Deploy Infantry, because they are cheap and may even shoot over walls. Juggernauts are the main attack power. Use your Hero to take out the towers, but send him in after your troops in order to protect him. Use your Hero's special abilities, such as the Helicopter. Work on taking out difficult reach defensive towers.
Resources
When you first start, concentrate on working with your resources. As you continue making progress you will need a stable source of currency, such as gold and oil, and Celenium as premium currency. Build resources that will earn oil and gold. Save your Celenium for permanent advantages, such as additional builders, instead of speeding up tasks. The best way to get gold and other resources is by conquering other bases. To do this easily, find abandoned bases and attack them. Abandoned bases have less defenses. You can tell if a certain base is abandoned if there are lots of overgrown trees. You can loot gold, diamonds and oil that you can be used to improve your resources.
