Level 5-18, 5-19, 5-20

Forget about getting gold on these levels. I can't even get Silver.

Anyone got any ideas or tips on how to accomplish that?

Thanks in advance.

I got 5-19 finally - at 8:13, too!

Sell 2 cows, then sell all milks until Boat, Warehouse and Cart are fully upgraded.
There will be 3 waves of Bears.
Don't upgrade any of the six machines past Level 3
Make 12 Wood in batches of 3 (with 3 Sheep)
Start making and selling Dresses, upgrading to Level 3 machines as you can with Wood
Once you've got your 12 Wood, sell the 3 sheep and start making 12 Granite in batches of 3
Start making and selling Cheese, upgrading to Level 3 machines as you can with Granite
Sell extra Milks throughout the level. Since they take up a whole Boat slot each, having 27 in stock is not helpful.

Good Luck!