Just as everything else. Practice. My advice is, dwell a little on batching before you start with your first graphics app. Also, use stbi_image.c to load textures.
Learn by example. Begin from very simple things. Understand it and move to the more complex one.
You can follow link in my signature for some code samples.
I recommend that you learn modern OpenGL (3.3/4.1), and use a cross-platform toolkit for window handling.
it’s the same question for me!Especially in china,there is no communication platform for OpenGL.so I come here by Google and I want to find someboy to study together or some masters to show me the right way.