Well I guess every country has its own sayings but in mine we talk in Spanish and we usually say:
¡Vamos! (Let’s go!)
¡Tú puedes! (You can [do it])
In Finnish one could say
Tsemppiä! (no good literal translation… means good luck. I think it comes from Swedish kämpa meaning to fight)
Pidetään peukkuja! or just Peukkuja! (Thumbs up! In Finland thumbs bring good luck like crossed fingers elsewhere)
It should be “Hazz muaffaq!”
In Arabic “حظ موفّق”
In Chinese, 加油, pronounced as Jiayou, literally means “refuel”.
It means “cheers”, “come on”, “don’t give up”.
Laura
In french there is many way to say it like “bon courage”, “bonne chance”, 'tu peux le faire"
And, after you have encouraged them, you can also add a wish for good luck by saying
In bocca al lupo! (literally: in the mouth of the wolf! Something like the English “break a leg”)
Well the Swiss call at sport events where a Swiss team plays “Hopp Schwiiz!” meaning Go Switzerland, Schwiiz is the dialect word for Schweiz in German.