I'll add some more refs for you, hands and feet are very similar in structure and both are difficult to draw so it's not strange if you'd struggle I think if I was gonna model a character he's be wearing shoes and boxing gloves
Structure of the foot goes like this: tibia and fibula meet tarsal bones to form the ankle joint. The bony protrusions sticking out on both sides are their condyles. The only visible tarsal bone is the calcaneus which forms the arch of the heel, these then meet the metatarsals that make up the main part of the bone structure of the foot. Look at how the phalanx meet the metacarpals and flex your own toes to determine how many phalanx make up each joint. I think your foot looks pretty good, but you have a bend in the joints that goes the wrongs way and breaks the arch of the upper foot. One thing you should try to do before modeling these structures is draw them up so you understand them, try just making some line drawings of the arches in different poses.
Structure of the hand: radius and ulna meet the carpal bones to form the wrist joint, and then continues with metacarpals and phalanges so the same as above, the bony condyles are visible. I remember I was very surprised that the metacarpals made up most of the hand, it's difficult to feel on yourself because it's reinforced by ligaments and muscle but if you do a spread and bend the fingers up you'll see it. If you flex your hand you'll see how the metacarpals end by the knuckles and you then have two phalanges for the thumb, three for the others. Also hold around a finger and slide along and you'll feel the bones get larger where they come together to form joints.
If you get the metacarpals you'll also understand the shape of the hand, try drawing the structures and add some wrinkles on skin for phalanx joints, knuckles where the metacarpals end and define the metacarpal bone that leads to the thumb, also the tendons that run on the upper side of the metacarpals can show slightly.