Language
The two official languages are Tagalog (Filipino) and English.

Credit Cards
Credit cards are accepted by many restaurants and businesses.  Most smaller establishments accept cash only.

Tipping
Many restaurants automatically add a 10% service charge, but leaving an extra P20 is appreciated (or P40-P50/person if a service charge is not included).
Round up taxi fares (for example, from P164 to P170), but consider tipping P20-P50 or more.
If someone helps you with your bags, tipping P20-P40 is standard.

Toilets
Toilets are commonly referred to as a CR (comfort room) in the Philippines.