The majority of the world don’t speak English, so you have to speak their language! Start with English and Chinese (Simplified and Traditional), Japanese, Spanish, French, German, Russian, Portuguese and Korean.
There are a bunch of services out there that will localize for you, ask a friend or try out a site like Fiverr.
Experiment
The only way you are going to know what works is by experimenting, try different wording and numbers. If your sales go backwards you can always revert.