1. First when your population is down very low start to panic and increase your Cottage level and make your Tax Rate lower.
2. Make a Farm increase it and use the scroll that will increase it and you don't have to panic if you can't just follow step 1.
3. Next you make your Sawmill so you can get enough lumber you mostly need lumber and stone so after making Sawmill follow step 4.
4. After making the Sawmill make your Quarry for Stone and once you get enough Lumber and Stone you can upgrade stuff faster then go to step 5.
5. Next build an Ironmine which gives you Iron. The Iron will be for the Forge so you can increase Military Science.