Study programming.
Study shading.
Study math.
Practice replicating visuals.
It doesn't matter what approach you take to it, if you're really interested in doing that(and if your idea of "anime waifu" is actual 2d and not the average western 3d-er's idea=pixar characters) the biggest limitations are going to be whether you're observant and intelligent enough to tell the 3d program how to show what you want it to, how you want it to, from the angles you want it to. And that requires math and programming more than anything else because that kind of NPR is based on 2d art is based on abstraction of reality, whereas realistic rendering is simply regurgitation of physical rules.
Or, if you're not that serious and you just want a little anime waifu character to mess with then yeah, go low poly. But in general, you should almost always try to stick to low poly as much as possible, moreso the better you are at programming and math(because if knowing programming/math enables you to not give much of a fuck about polycount due to the fact that almost everything is transferrable between a lot and high poly mesh since, speaking in terms of the object you're modelling as an abstraction, they're the same thing represented with a different level of accuracy).
Anyway if you've got none of the skills I mentioned and your goal is something like the OP image then don't touch high poly, I suppose. High poly is great and all but it's very difficult to manage compared to low poly, which is subdivisable in most applications anyway. The long and short of this post is that you should only work with high poly if you can afford it in terms of your technical knowledge.