You can find two yellow rupees on the roof of Colin's house. To get up there, jump onto the mailbox, turn around and jump to the roof angled a bit to the right.
In every category besides 100% you only do Goat Herding once having to herd 20 goats.
Besides being open to personal preferences and adjustments, two routes emerged over time. No matter which route you take remember to not press A at the start to prevent Link from talking to the farmer and not use A too often cause else the goats will chase you.
A good goat herding with this route will average between 19 and 24 seconds.
This route is a bit more likely to fail though but faster on average.
The movement in the beginning can vary, its safer to delay the first whip for a bit.