For the beginners, before beginning the preparation, syllabus and previous years’ question papers makes one familiar with the exam-plan and related requirements at each stage. It gives a fair idea about the requirements and the exam standards.
In the beginning it would be really difficult to analyse and solve these papers but, when you will prepare, you will easily figure out which topics and issues are often asked in question papers.
This will help you figure out the important topics and later on will help you guess what all can be asked in examination and will help you prioritize the important ones.
Now, the way questions are asked in examination, the basic understanding of the topics becomes the need and the level of preparation should be such that matches with the exam-standards.
As you move forward, solving these question papers give you confidence and make you aware of the areas where you lack.
Again, solving these question papers help you in ‘Time Management’ as you can make out how much time one question take and were you able to manage question in stipulated word-limit as well. If you are able to develop this skill with practice, it would be a great achievement and will boost your confidence.
Previous years’ Optional Subject's question papers for Civil Services Examination are given here for your reference.