Learn to follow God’s instructions clearly no matter how much it seems impossible. God told Joshua to make Israel’s army march round the city of Jericho with the Ark of the Covenant once daily, but on the seventh day, march seven times then blown the horn loudly with a loud shout from the army. This they did, the walls of Jericho fell, and Israel took the day. Always keep you promise regardless of the race, gender, or religion of the one you made the promise to. Just as God kept his promise to Israel, the 2 spies kept their promise to Rahab and saved her entire family from destruction for hiding them when they were in need. Joshua also placed a curse on whoever tries to rebuild Jericho.
The sin of one man can pollute the land and bring suffering to a nation. Achan did what he was not supposed to by taking what was meant for only God from the spoils of Jericho. It was because of one man that a nation lost a battle to an insignificant opponent. Never take what does not belong to you, just because you can or have a legal system that favors you against your neighbor. Achan was destroyed with his family and all that he had. Obey God, do what is right, and live.
Joshua laid an ambush for the city of Ai. He kept some men behind it and attacked through the front. When Ai came to fight, Joshua pretended to retreat so that Ai could pursue Israel, but it was all a trap. While the people of Ai chased Israel into the wilderness, the ambush behind Ai came into Ai, captured it, and burned it down. The people of Ai were in confusion when the saw their city in flames and were surrounded by Israel in all corners. Even when God is with you, you still have to use you senses, brain, and have a strategy.
Always seek counsel from God before you make a decision. When making decisions on major issues, ask God that he may show you any deceit or trickery. God still talks though the mind, conscience, and dreams. When there is something in your mind and you ask God about it, God will answer. Just wait on the lord. Try not to make any unholy alliance with deceitful and tricky people, who are always in for a gain based on lies.