Wünsch mir Glück!

Wünsch mir Glück - that is the literal translation and it is correct! Don't be astonished if you get the answer "Hals- und Beinbruch". That does not mean someone wishes you ill - it is just a German saying for wishing someone luck. So instead of saying "Wünsch mir Glück" you could as well say "Wünsch mir Hals- und Beinbruch" ... and it is quite common to do so!