I don't think not using at all is a good thing. Surely you must have some utility payments every month just use the card for that. Keep the credit utilization below 30% and you are good to go.
Another suggestion: Get IDFC Wow or any other FD based credit cards and do some spends. It will help in score improvement. As a thumb rule do some spends on existing card, but don't cross 30% of the threshold limit.
As many of the members have already suggested, keep usage in the range of 10-15%, pay bill on time, that's it.
Bonus tip- if you are someone who remains busy and may forget the due date, just enable autopay. And watch your CIBIL grow.