What is a giveaway for?
The more people who enter the giveaway, the faster it will be shared and the more potential followers you will reach. That's basically what a giveaway is all about.
There are 2 types of audiences participating in your contest:
who already follows you (your followers, who may be more or less active)
who doesn't follow you and probably doesn't even know you but arrived at the key features of paytm post where you launch the giveaway through a strategic hashtag that you inserted (great idea!)
Now the question is: if the point of this type of activity (an Instagram giveaway) is to reach and convince as many people as possible to participate, what will help you engage the 2 types of audiences mentioned above in your contest?
In the case of those who already follow you, you have to be good at putting yourself in the shoes of those who are already your followers and understand what will capture their attention. If your Instagram page represents your e-commerce , your followers are probably already your customers or people who are very interested in your products, who are just waiting for the right opportunity to make a purchase. As a prize for your giveaway you could offer one of your most sought-after products: this will not leave your audience indifferent. If you are a hotel, a wellness center or a gym, you could offer an exclusive experience in your facility. Are you a professional? Why not put a consultancy up for grabs?