There are three objectives that must be completed to earn the maximum amount of stars and coins. Simply completing the mission guarantees one star. Do not spend coins to respawn in single player mode. Save your money to buy advanced tank parts. Only purchase items that are required to earn stars.
Coins
Tap the "Free Cash" icon and watch a video. Besides defeating enemies, you can also earn coins by destroying the objects in each level. Collect the coins that may appear and complete the level to keep them.
Combat
Play cautiously, especially in small areas and assume that every enemy shell will ricochet.
Multiplayer battles
Similar to Campaign battles but you and your opponents will respawn, and random power-ups such as health and missiles will appear. The goal is to earn the most points within the time limit rather. Although you will not earn stars, you can play them to earn coins. Shoot at any target continuously. Unlike the CPU, a real opponent will probably be moving constantly. The more of your shells you have in motion in your opponent's area, the more likely you are to hit them. Shoot at the power-ups. When health and temporary upgrades appear, players will rush to collect them. By firing a volley at the items they are trying to collect, you have a chance to take them out. This also increases that chance that you will be able to collect the power-up. Learn to shoot while moving. Also, use cover whenever possible.