'Good Luck' in Tagalog
Most Filipinos actually use the English phrase "Good Luck." The following Taglish phrase is a common way of wishing a friend good luck:
Good luck to you.
If you insist on a Tagalog phrase (and to many Filipinos' exasperation, most foreigners do), then you can try a literal translation or an old-fashioned phrase.
(literal translation; no one uses this phrase)
Pagpalarin ka sana.
Hope you have good fortune.
Sana swertehin ka.
Hope you get lucky.
(colloquial, but is slightly different in meaning)
Remember: the Philippines was under American rule for half a century and even after independence in 1946, English has continued to have a strong influence on Filipino culture, especially the language. Many Westerners think that by translating every single word into Tagalog, they are making things easier for Filipinos to understand. In many cases, it only makes the situation needlessly difficult.