passport, birth certificate,
if working = employment certificate , if student = current and future status, enrollment papers
proof of financial capacity for the entire visit.
optional = ID's (company, SSS, NSO, Driver's)
if visiting a family relative -- your relative should also attach the same documents plus an invitation letter with details of significance of your visit. (celebrating an occasion etc etc)
if visiting as a legit tourist -- optional itinerary (hotel booking, flight booking --kahit yung unpaid pa pwede na)