Hi Rishab, there variety of things you can do in Goa- Beaches, Nightlife, Adventure Sport, Food raid to local food, Shopping, Casino, visit old Goa churches and streets list will add 10+ more depending upon your interest area you can choose what to do and places and itinerary will change accordingly. Below is my favorite places and things- 1) Visit 7-8 beaches depends upon mood south go or North Goa
2) Ritz classic for lunch or dinner in Pujim you will get reasonable, hygienic authentic Goan dishes including fish here 3) Visit Casino in Punjim evening time
4) Old Goa
5) Shopping please ask if you have any more specific query
If you want to experience the nightlife of Goa, then must visit North Goa and if you prefer some alone time or a quiet walk on the beach or on the streets, South Goa is the place to be. you should visit Baga, Calangute beaches etc. Do let me know if you need any information. I recently visited Goa and can give you the itinerary if required.