Da Lat is connected with the rest of Vietnam by air, train and bus.
There is no direct flight to India from Lien Khuong Airport. First, take a flight to Hanoi or HCMC (Vietnam Airlines) and then a domestic flight to Lien Khuong Airport. You can also take a bus.
Taxis are usually costlier than bus services. Nearby domestic travellers sometimes travel by their own car. Although cabs are available at Thap Cham Railway station too.
Another exciting route is the high road that connects the beach destination of Nha Trang to Da Lat, a scenic pursuit in itself. However, be sure to have a valid drivers permit if you are planning to self-drive.