As you wish to appear in CSE 2015, you have enough time to prepare for Civil Services Examination. Being in job makes preparation little tricky as you get limited time for study; but, the end result is such that keeps you motivated and inspire to put in the best efforts.
Right now, we suggest you to understand the complete exam-plan and related requirements at each stage. This will help in better planning and self-analysis would help you in prioritizing your study-plan as per your needs.
Self-help is the best strategy in the beginning and NCERT Books are the best resource for laying a solid foundation. Daily newspaper reading would help in building awareness and knowledge that you require to face the examination effectively.
You need to understand that it not about being specialist; you have to develop insights about things and should be able to relate the information that you read and remember.
Proper planning would make things easier and adopting integrated approach for preparation would help you in managing things in limited time.