3D models: converting from binary file, learning to read hex dumps

Question

I have a 3D object stored in an unknown binary format. I opened it in a hex editor and noticed that the first line said "OBJF", followed by some lines that were translated as material and texture names. So at least I'm convinced it's a 3D object.

Now I need to figure out the vertices and normals and UV's and maybe other information, but I have no clue how to figure that out. So I will need to learn how to read hex dumps somewhat effectively before trying to guess at what the data might represent.

Where should I start?