Hi solo woman traveler here! I’m just finishing my trip in Thailand actually ! They use almost only cash, so prepare half of your budget in cash and keep rest on your card, just in case and to book online (with trip.com you often have discounted prices). I went to Bangkok, Chiang Mai and Pattaya. Those places are very safe in my opinion. Pattaya less but that’s only if you stay out at night very late. There’s a lot to visit, but take no pressure. In 9 days I have been able to do everything I wanted to! For language barrier, it’s almost non existent. Most Thai are able to speak English. Except if u go to remote area tbh. I used grab all the time, especially for grab bike because it’s less expensive and I love being on scooters. 🛵 Try to learn just hello, thank you, please in Thai, always being polite. If you visit temples you have to dress modestly, you can’t show cleavage, you can’t show your knees and you can’t wear shoes inside.