Car hire is the most flexible way to explore larger islands like Crete, Rhodes and Corfu. Book well ahead for summer. Greece drives on the right. Confirm licence, insurance, fuel-policy, age and child-seat requirements directly with your chosen provider before booking.
Ferries / island hopping connect most islands, especially within the Cyclades (Santorini, Mykonos, Naxos, Paros) and Dodecanese (Rhodes, Kos and Symi). Routes, timings and availability are seasonal, so confirm them before booking. Check whether a rental agreement permits taking a hire car on a ferry before making plans.
For a first Greek islands holiday, many UK travellers find a single-island stay simpler and more relaxing. Crete, Rhodes and Corfu each have enough variety for a two-week holiday without needing to change islands.