Getting to the island is rather an easy task. Two well respected Olympic air and Aegean air have regularly scheduled flights everyday all around the year from the international airport of Athens, and from the international airport of Thessaloniki during the summer season. From spring till autumn international travelling to Santorini can be even easier and cheaper since many charter flights come from all over the world. You may consult your travel agent or have a look at various sites on the internet.
Of course there is also the possibility of traveling by ship, a regular or a superfast one from Piraeus port. Do not discard this possibility, you might be surprised how comfortable this might be! Have a look at the schedule here: