very interesting challenge! i will probably give a try but time is very difficult to spare lately 
mnmava you are going for a very dificult one, so good luck, and as AngelJ mentioned it, only having fun matters here 
and i would add that some peaple might not be very good at modeling or drawing but have an exellent understanding of anatomy in its “mathematical” form,others have no clue how you call this muscle or this one but have an amasing ability to reproduice human form …all that to say that any chritisism should be welcome as long as it is productive for the artist
Anyway, back to your art…here are some advice:
you are trying to reproduice a 2d drawing using a 3d media, but i suggest you focus on the detail that you will mostly see on your final piece, here, mainly her “front”.
You also go high in subdivision to early…i would start by getting the form of the femal warrior in a low rez subdiv, usinmg the drawing as a background to position her and get her to fit the right angle …you can probably store it using one of those brilliant script you can find in the forum, like the reference image one, then after getting the right shapes, starting detailing all the needed area, getting back to its pose using the refimage script,etc…
again, this is just a workflow like any other…just thought you might want to have my opignion
happy zbrushing
(