Goa has some of the best beaches and Churches of India and combined with the cultural fests, night life, food and water sports (has some of India’s best Scuba diving locations), it comes with a complete package for a vacation! The beaches of the farthest North (Candolim beach, The Baga beach, Calangute beach, Anjuna beach and Arambol & Vagator – the less crowdy) and the farthest south (Palolem beach, Patnem beach, Agonda beach and Cola beach) are the best. Spending 2 days in North Goa, 1 day in South Goa and 1 day for the shopping would be a good agenda.
I would also suggest driving to Malvan (2h 30m drive from North goa) to experience the best SCUBA diving, Snorkeling and many other water sports in the secluded beaches. Best time to visit Goa is during the winters (November to February) when the weather quite pleasant. Also, you try visiting in the monsoons (June to September) which brings a unique beauty to Goa’s landscape and most importantly, you get a good discount for your accommodation!