Rail: The two main stations on which you can reach the Gir Forest are the Junagadh Junction Station (JND) which is 55 km from the forest and the Veraval Junction Station (VRL) which is 45 km from the Forest. From there you will have to either take a cab or take a bus which runs frequently from there. The journey takes about 1.5 to 2 hours.
Road: Gujarat is known for its beautifully maintained roads so a road trip can definitely be on the cards. There are three major places by which you can plan a road trip. Ahmedabad is 410 km from Gir and can be reached by National Highway 47, Rajkot which is 160 km from Gir can be reached by National Highway 27, and Diu which is 110 km from the forest.
Air: The closest regular airport is the Rajkot Airport (RAJ) and receives daily flights from Delhi and Mumbai. Diu Airport (DIU) is much closer and can be reached exclusively from Mumbai.