You can start by identifying the argument structure, i.e., premise, conclusion, etc. You can practice this while reading anything. Try to understand what the author is saying, what is missing, and why a particular sentence is there. Always go from wrong to right, first eliminate the wrong options, it will be much much easier to arrive at the right answer.
Another thing that helped me when I was stuck between two options was the negation technique.
And PRACTICE! Practice different types of CR questions to familiarize yourself with various argument structures and assumptions. After answering CR questions, review the explanations, especially for any mistakes, to understand the underlying assumptions.
Good luck with your GMAT preparation!