This is just my know-how, and I hope that it can be helpful to you.
First of all, this game character was to be made through the Unreal 3 Engine, and this character illustration was for commercial purposes. However, for several reasons, the project couldn't be completed.
The character is a fusion-style SWAT solider of the near future. He is able to conduct some magic, jump high, and his clothing is based on a contemporary design. I didn't know too much about SWAT clothing when I started this concept, so I gathered some images for reference (Fig.01).
First of all, the low-poly model was created in 3ds Max. Since the game was to be produced with the Unreal 3 Engine, the body was exaggerated (Unreal Engine's field of view is very wide). The low-poly model that was produced in 3ds Max was then shaped roughly in ZBrush. Since it was going to have bullet-proof clothing with many accessories on the clothing, it didn't take too much time to produce.
The rough ZBrush data was then taken back to Max and the accessories and bullet-proof clothing were made using the basic body line as a guide (Fig.02).
The items shown in Fig.03 were then designed and created in ZBrush.
The normal and cavity maps that are required for high-poly mapping were taken from the ZBrush data for each part.
I imported the mesh of each ZBrush part and processed the mapping, after applying the basic materials in high-poly (Fig.04).
I extracted the complete map, diffuse map and normal map using the render to texture function (Fig.05).
I then extracted the occlusion map and tested it in the 3ds Max and using the Unreal Engine. I used 1024 map sizes for each part (head, body, arms etc.), and made the diffuse specular normal map.