Answer:
There are many factors to getting better at art, including value.
Step-by-step explanation:
Reference photos (as stated in the question) are a simple way to do this. You asked for a way to get better at using reference photos (As you already know haha.)
Anyway back to the answer-
There are a few ways to get better at using ref photos, some artist (even though many frown upon) start out by tracing- (technically many of us did this when we were little anyway- i.e: coloring books, activity pages, etc. )
Tracing can help you improve your coordination and steadiness in your hand as well as give a basic idea of hw to draw more complex shapes.
I also suggest practicing, try finding simple photos and then go from there.
Find the basic shapes in each part of the art (i.e) triangles for a wolf's ear, or a circle for the head) these will help you to form the basic structure of the drawing, then add your line art and details.
Basically, if your one of those TLDR people, "practice makes perfect" is the idea in this case, weather your tracing, or finding basic shapes, the more you practice at this the easier it will get.
Getting better at value can also be done by adding both lighting and shading to the art, as well as small details such as fur direction or clothing wrinkles.
Hope this helps :P
Have a nice day, you wonderful being! <3