i. Rent a car in Athens and enjoy the drive.
ii. Go to the Larissa station in Athens, take the train, go to Larissa. Rent a car and enjoy the short drive.
iii. Take a package tour: http://www.partner.viator.com/en/3888/tours/Athens/2-Day-Tour-to-Meteora-from-Athens/d496-31408A
You should also be able to take a train from Athens to Kalampaka and a bus or hike from there.
by car using the gps,google maps or michelin....or to be more classical a paper road map...:)
or the ktel bus from athens to trikala (almost every 2 hours) and after the bus trikala-kalambaka that is every half an hour...