Flights Hotels Travel Insurance all paid prior to arrival obviously.
Always take cash to survive on (Exchange at a Thai Bank ONLY) when needed or most of the time and have the (WISE APP) account to deposit funds from home bank account to (WISE APP) if an emergency.
Wise has minimal fees and real time equal exchange rates.
Been to Thailand 10times since 2008 including 4times in the past 2years and have never been asked for proof of funds to survive on.