We have been doing island hopping in Greece multiple times and love it so much! Consider starting from Athens or one of the bigger islands like Crete. From there to easily can reach popular islands like Santorini and Mykonos. Use ferries for transportation and plan in advance during peak season. Off season we didn’t book anything in advance but it can be a good idea. Though we recommend to plan as little as possible to be the most adventurous. We have been visiting almost all of the bigger Greek islands and a lot of the smaller ones, so if you want to know anything specific please let we know