15) Keep in mind the types of troops, and their advantages and disadvantages against each other.
Infantry troops are strong against demolitions troops. Vehicle troops are strong against infantry troops. Demolition troops are strong against vehicle troops. Infected troops (all of the zombies that you can train in the infected pen) are weak against every single one of the living troop types, but are strong against wall defenses. Living troops are weak against wall defenses.
14) Concentrate on upgrading your farms more than your other resource-earning buildings.
Your food will run out fast because for each troop that you have trained, you’ll use up food to keep them fed, so food disappears far more quickly than oil, wood, coins and metal do. Build more farms and upgrade them all to high levels so that you can handle a huge influx of troop training.
13) Upgrade your wall and train defenses.
The same principle applies here as far as the numbers game goes. Train as many defenses as possible. The higher level your wall is, the more you’ll be able to train. Unlock new wall defenses in the research lab to beef up your fortifications, and for defenses which have specific strengths against troop types.
12) Get attacked in the middle of training? Send your troops out into a wild or the wilderness to keep them safe.
Nothing is worse than having troop training derailed by another player who won’t leave your alone. Your radar screen should be upgraded as high as possible to warn you of a marching unit that’s about to attack you. When you see the warning, send your troops out so that you can save them from being attacked. This helps to prepare a strong army over a long period of time, so that in the future when you get attacked, you can hold your own.
11) Upgrade your hospitals and your cloning center as high as you can.
The hospitals are used to revive troops that have been killed in the defense of your city (not in an attack against other players), so the more hospitals you have and the higher their levels, the more troops you can revive. The cloning center will revive your hero if they are killed by another player, but if you have ignored upgrading it, you’ll lose way more experience points than you have to. The higher your cloning center’s upgrade level, the more experience you’ll keep when all is said and done.