i usually have two approaches: ‘outlining’ and ‘simple ‘construction’
most of the time i won’t even draw all individual fingers but just merge them together or try simplifying by breaking the hand/foot down into shapes, that will make it easier to ‘construct’ and pose.
unless you want to draw stuff for feet/hand fetishists or have a very ‘realistic’ style you don’t need to over do it with the detail.
of course the easiest way is to use reference, just look at your own hand and feet…unless you don’t have any, but there’s google. I don’t know any ‘specific’ books on that but there is ‘’Drawing Dynamic Hands by Burne Hogarth‘’ you could check out.