By hardly using your card at all. [Yes.] From among all the options available, this is – in my opinion – by far the most reliable one.
Non-usage of the card
[= almost no use at all] provokes HDFC to believe that you’ve perhaps forgotten that you hold a HDFC CC to begin with; in which case, they ignore you, and forget you as well.
But if you use their CC regularly, but for very meagre amounts, they tend to believe that
(i) you use CCs regularly;
(ii) you use your HDFC CC regularly as well;
and hence, would probably keep using it more – and for heavier amounts – if some more incentives are given. Which is why they then trigger a limit enhancement.