Realism goes a long way, especially in the anime style. Whatever your case may be, I'd suggest using actual photography as reference material, since art references can be drastically different and changed simply by it being a matter of style and how a person draws feet. They may be missing things that are important to add that are not there, or are adding things that are unnecessary and unrealistic. This can really confuse someone who is trying to learn since everyone draws a little differently and some have a preference for complete realism, a blend, or complete cartooney exageration. If you copied any particular way, you'd be learning how to draw like THAT artist, and then you'd just be a copycat and wouldn't be taking advantage of what realism has to offer or what you have to learn from it.
By using realism you get realism, and it's not modified or made uncertain by another artist's understanding of it (or lack thereof and inexperience). By going with realism, you're exposed to how feet should be drawn on a realistic style figure, and then you're open to create your own style, as opposed to merely copying somebody else's. Using art to draw art can be a liability, since you may be learning mistakes as well, thinking they're correct, when in fact you're learning how to do it the wrong way because the artist of the reference material goofed up and isn't doing it right either and is him/herself inexperienced.
Realism won't lead you astray because it's not about experience or style, it just is what it is: real. It shows you how it needs to look, and you need only follow that and recreate it. It will take a long time to get it right, but it's better to start off this way. Also, realism will always be with and around you all the time, with or without photos. Styles change and come and go. Realism is forever.
Realism is your friend. Make use of it.
