Draw your own hands and feet.
Break up the hands and feet into simple shapes while keeping in mind the natural movement of each part of the hands or feet. For hands specifically, also keep in mind how the parts of the palm fold over when carrying objects.
Now I don't normally draw feet often because characters I draw often have shoes. Anyway, I basically draw a simple shoe shape for the flat underpart of the foot. Then I draw that ramp looking shape in the front of the foot and then the ankles from there.
Here are some tutorials you can look at. Links 3 are in Japanese, but they're generally is about turning the hands and feet into simple shapes so you can construct them easier.
Hands: Link 1 Link 2Feet: Link 3Yeah...and there's plenty of art anatomy books on how to construct hands and feet too. So you can check them out on your own.