Increase your battle rank whenever possible to get more time to attack. Do not deploy more troops than necessary to win. When attacking, focus on looting resources. Alternately, set your goal to win and destroy everything.
Defense
Use the moat to limit the routes into your base. Instead of positioning defensive structures at the entrance, set a decoy building there to stall enemy troops. You can also spread out your structures to not allow your enemy enough time to reach all your buildings.
Starting tactics
When first starting, you will be protected from attack for two days. Use this time to build resource producing buildings and silos first, then upgrade them to the maximum amount. Complete single player missions until they are exhausted for resources. Save your Medals instead of spending them to quicken resource production. Medals are better used to get a third builder later. After your resources are set up, build your barracks and upgrade your troops. Increase your Headquarter levels then finally build as many defenses as possible. Position to protect your resource buildings.