There is a dozen of hotels near the beach for a reasonable price. Find hotels in Ao Wong Duan
How to get there 
Fly to Bangkok International Airport - Suvarnabhumi (BKK)
Taxi directly from the airport to Pattaya costs about 1500 bahts. Make sure to negotiate the price before the trip to avoid surprises. Journey will take from 1.5 to 3 hours depending on traffic.
There is also frequent bus service between the airport and Pattaya. It departure from Level 1 (Doors 7-8), costs about 150 baht per way and goes about 2 hours (or longer if traffic jams).
You need to get by bus or by taxi from Pattaya to Ban Phe
town, and next take a ferry to Ko Samet island. Some boats get directly to the beach of Ao Prao.
The main transportation option in the island of Samet is by "songthaew" (some kind of shuttle mini bus). Find flights to Ao Wong Duan
When to go 
Try to avoid September and May, - these are the rainiest months on Koh Samed island.
Water temperature, C
Wind speed, meter/sec