Gold
Upgrade your gold storage as soon as you can. The maximum amount of gold you can hold at one time when you start is only 1,000. During the tutorial you will have to build a gold storage, which increases that amount to 2,000. However the Reeking Rogue camps that can be raided at the start can result in 2,000 to 3,000 gold. Upgrade your gold storage to avoid wasting that excess gold. A level 2 gold storage will increase your capacity to 7,000 gold.
Units
Each type of unit does double damage against a specific type of enemy ro structure. For example, the Scallywags will do double damage against resource buildings, such as gold and rum storage structures. Scoundrels will do double damage against defensive buildings, such as rifle towers. Pair units with each other to make them more effective. For example, enemy Rifle Towers can take out your Scallywags with a few shots. However Scoundrels can take out towers pretty easily, but are even weaker than the Scallywags. To take out the towers effectively, send in a group of Scallywags to get the attention of the tower. Then, quickly have your Scoundrels attack from behind.