Build more guilds than forges. Hire allies - the more money you invest in allies, the more you will make per atk. This is crucial - and combined with active play you can lc in 2 weeks
The only correct answer is "it depends". If you have access to farms, then you should go with a single beastiary & make every other bldg an l3 guild. You should maintain ally plunder at all times and should only upgrade when you have sufficient funds in excess of what's needed for max ally plunder. If you do not have access to farms then you will need to take a more aggressive approach by building forges instead of guilds until you have sufficient strength to hit targets that pay well. You then want to maintain as many guilds as is possible while still being able to hit targets. In this case you should search for inactive targets that have a low defense relative to your attack but higher overall stats than your own. You will need to upgrade inactive targets as you grow.