I think there's a cultural mismatch here. It's actually very difficult to think of a natural valediction in English that wishes someone success without invoking luck. You might like to consider the following comment on the expression "Good luck!" in the
Webster's New World American Idioms Handbook (which bears out what Phil has said):
"Saying "Good luck!" is a common way to wish someone success in any endeavor or effort. For example, a person might say "Good luck on your exam" or "Good luck in your new job." In some cultures, wishing people good luck is a bit insulting because it implies that their skills or intelligence are not adequate, and therefore they need luck to succeed. But in American English, saying
good luck is like saying, "I wish you much success; I wish you well."
http://books.google.es/books?id=m7le7O8KAEwC&pg=PT230&lpg=PT...