Best way to make legs?

So I've got a commission coming up that is going to have legs and arms. I know how to do the arms but not so sure on the legs. I'm assuming separate feet and legs like the arms and hands? Also if I do that how high should the ankles come up/how long do the legs come down over feet. Also what is the best way to keep them attached together after being put on?

Thank you guys, just want to make sure I do this right