Number of days depends on what all you want to see in Goa.
for sight seeing you can visit following places
1. Old Goa church, Aguada fort.
2. Goa has beautiful beaches. north Goa beaches are little crowded. You can visit baga beach, calangute,Anjuna,vagator, Dona Paula in North Goa. If you want to be away from crowd u can visit betalbatim, palolem beach in South Goa.
3. Goa is known for its beautiful temples, you can visit Mahalasa temple and Mangeshi temple, both are very close to each other.
4. If you are interested in History you should definitely visit Ancestral goa. http://www.ancestralgoa.com/
5. Don't forget to visit Chapora fort for an amazing view/ sunset
6. Spend an evening on Mandovi River Cruise. On the Cruse u can witness Goan dance and entertainment programs. 7. For night life u can visit baga beach, there are many pubs like Mambo, Tito 8. For shipping visit Anjuna beach flea market on Wednesdays or Mapusa market.
for cashews visit Zantye
9. Below are the good sea food restaurants
Ritz classic 10. You can visit doodhsagar water falls. it's a one day trip. Check the below link for more details.
https://dudhsagar-falls.com/tour/dudhsagar-waterfalls-tour-package-goa-india/ Wishing you a great trip.
I'll tell you about the places I've personally been to. 1. Beaches to spend an entire day- Morjim (NorthGoa) https://www.tripoto.com/trip/a-day-at-morjim-beach-5e09fc1601f33 , Palolem. You can just lie and enjoy the beach and get tanned. You'll find everything you want to eat and drink and smoke at the beach.
Arambol beach in North Goa is full of hippie vibes. 2. For Sunsets- Benaulim beach https://www.tripoto.com/trip/goa-for-peace-seekers-5e088518e6a67 , Vagator, Chapora fort. 3. Clubs- LPK, Mambos. If you want an experience of a chilled out pub then you MUST visit Soro- the village pub in Siolim- North Goa
4. Places of Architectural interest- Aguada fort, Chapora fort, Sinquerim fort.
5. You must try out hostel stays in goa if you're traveling solo. 6. If you want to just sit and have few drinks with loved one then theres a place called Mango tree in Vagator. Its a chilled out place and there's no chance you won't enjoy it. The ambience over here is too good.
U can reach goa by air ,road or rail .if ur a party person then north goa has it all and if u are a peace and nature lover longing for peace then south goa is for u .when it comes to stay from 500 to 2lakh u have wide range budget stays visit booking .com for ur preferences.food -art cafe,sundowners ,eva cafe ,leela cafe,thalassa ,brittos,souza lobo.off beat places _palolem beach ,honeymoon beach,basilica of bom jesus (old goa ),dona Paula,spice plantation (ponda ),church of our lady of immaculate conception ,fort of agoda.