Best time is Oct-Apr. Get to Guwhati via air or train and then travel to Meghalaya Guwhati to Maghalaya road is a pleasing one. Or you can directly flyover to Shillong air port You can hire self drive zoom cars in Guwhati or it is easy to hire a cabs in Shillong and Megahalaya. Every hotel will arrange cabs or even driver on request.