My older teammates advised me to get all buildings to Level 11 then concentrate on getting Stronghold 20. Simple advice but helpful.
The Watchtower is a huge source of food and iron. Gryphonkit, my wife, always kept her Stronghold and Watchtower the same level.
Exception: Do not level Barracks until you have a rainbow 4* 3.60 team. Troops require an insanely high amount of food.
Beginner links
([Analysis, Math] Minimum buildings for Training Camp 20- Updated 2019-Jun)