There are many categories in smartphone industries today namely
a)Budget (Below-₹10000)
b)Mid-Range (₹10000-₹30000)
c)Higher Mid-Range (₹40000-₹60000)
d)Premium (₹60000-₹90000)
e)Ultra Premium (Above ₹1 lakh)
Choose your pricing accordingly.
One way to decide is to Observe your Current (old) smartphone, look for pros and cons of the phone. Look what your last phone lacks. Other way of deciding is to look what current trend is using the technology sites and channels on YouTube. We have given a detailed current Generation Smartphones Down in the link.
After picking your pricing look for your phone in different brands Start with the Companies which are in this market for at least 10 years. Go for Popular brands like Samsung, Apple, One Plus etc
In Festive seasons Online and offline markets have great deals on smartphones if you have a mid range budget in these season you can buy premium phones at low prices. So I recommend you to Buy a smartphone in these seasons for a better deal.