We give you three tips en one note:
Tip 1 Bring a spare smartphone and buy a Thai sim card at the airport, so you can always use the app.
Tip 2 If you stay on the mainland rent a car, a convenient way of moving around.
Tip 3 Be spontaneous, don’t plan your vacation. It can rain at the Eastern Seaboard while it is a sunny day at the Lower Gulf and the South Andaman. Check the weather apps.
Note 1 The cleanness of beaches varies because of the weather and seasons. A beach can by super clean day one, and after windy days the coastline can be with rubbish. I have been to beaches that were perfectly clean during a first visit but polluted during the next visit. Most of our hotels clean their part of the beach.