I booked a plane ticket to Poland and arranged accommodation with Esperantists using Pasporta Servo. Since my hosts didn’t speak English and I was travelling alone, I had to become fluent in 6 months, or else I’d be in trouble. I managed to do it, and the trip was incredible. I already feel like I’ve gained more than I’ve given with Esperanto.
My top tip: To expand your vocabulary quickly, make audio recordings of vocabulary lists, with a pause between each word. Play them in your car and guess the correct word aloud during the pause.