Making realistic character even fantasy character is not an easy task so the step by step tutorial is almost too impossible to write. But making of article can be very useful as the example of different tasks that has to be done in order to complete such project.
In this making of I will show you one of common workflow used in the game and movie industry.
First thing to do is gathering reference images for studying the character, more you get yourself familiar with the subject, you will model more successfully the final model.
Next thing to do is building solid base mesh. There are many techniques for building the base mesh but I found that most easy and artistic way is to sculpt hi-res mesh and than retopologize it. For this task I use ZBrush and next image showing retopologised mesh that can be used later for many projects.
I used the same technique for the rest of the body then I use 3ds max for stitching different parts together. After building base mesh it is time for hi res sculpting, that is where the real fun starts.
Using ZBrush standard tools, in the few hours I build hi res sculpture containing over 12 million polygons. Most important advice I can give for sculpting is to stay patient and not to rush with dividing your model too soon but focus on the overall form of sculpture, wrinkles and pores are the last thing to do.