Hello,
Civil Services require an exhaustive amount of studies, and its really appreciating that you are willing to start preparing for them at before starting your engineering. Just be thorough with the syllabus, as most of people start studying things which are of no use in the exams, analyse topics, read news papers, yojna magazine. And by the time you finish your engineering you will be ready to crack civil services examination.
But keep in mind you need to consistent with your preparation.

All the best.