Hey Jvr5035! I recommend building maximum amount of medical tents, maximum war tents, and maximum farms.
At keep level 19 I have 8 war tents, 9 hospital tents and 9 food farms.
The war tent is the most under rated building, when you have, for example, 8 war tents level 10, you will have 80% faster troop training and 240 additional troop training capacity. Maximize your war tents and it will help you train faster than whales who spend tons of money.
Maximize your hospitals so you are strong even if you get zeroed.
Maximize your food farm so you can train soldiers every 5 hours without spending money!