Yup its a great start, lotsa mora layas though or in english..Ain't Finished yet..Think of that as your color base map, now just work a reverse sequence of darker grey, a medium then light grey, through to a white layering sequence of hair strokes, that will build that darker grey patch back into the whitish look of the reference, ya could then match this with some light greys into your white area's, there will prob be some browns and other locally reflected colors in there somewhere to (Though didnt look real close), just naturally build it up and down through your color scale for that color ya see in the reference, the idea in depth is 95% of your initial layer may not be seen but its those darker shadow area's but ultimately they are still the same color hair, just deeper in so we want to see some of them overlapped of course by closer layers to the camera, chris cross that earlier base you've done with a lighter layer but still allowing a percentage of each layer to come through, that way it lloks natural, unlike erasing or scratching sometimes can do if overused...The trick is with animal portraits of not being afraid to paint dark to light, few do this well.most prob think its breaking a rule but there is no other way to get that realistic effect than to establish a darker base which you have and then by gradual addition of white to your hair color, keep layering your hair back to that lighter color shadowed look, but not completely covering each earlier layer, this takes a long time due to the slower build back into a highlight....Long story short, thats why some prefer scratching as its easier and looks nearly as effective, fur can be tricky with scratching as ya gotta know how to blend the hair base back in, but knowing how to go from the traditional light to dark, then reversing it from dark back to light is bit of the trick with opaques..You don't have to go crazy with the amount of layers as we can cheat a little with transparent overlays to finish it off and often re-color match as ultimately adding white to our colors to reverse the process in some occasions causes chalkiness or color shift, blending transparent layers over the top turns it all back to richer more tasteful and realistic colors.
Well that's the way I'd do it...LOL, hope that helps a bit m8, but remember with photorealism its all about everything being layered together correctly in the correct sequence so it looks as realistic up close as it does from a further viewing distance..But it ultimately also depends if ya have 40 hours for each painting LOL