Why are HongBao given?

The red packets are filled with new dollar notes and represent good fortune for the coming year. It represents good wishes from the giver.

Why must the amount of cash in the HongBao be even-numbered?

There's a Chinese saying that "good things come in pairs". Odd-numbered amounts are generally associated with money given at funerals.

Why can I open my HongBao?

It is generally, HongBao are given by married couples. But in Singapore, some newly-married couples are excused from giving HongBao during their first Chinese New Year as husband and wife.

What else should I offer when I go visiting?

As a sign of respect to one's elders and friends, two oranges must be taken along when visiting. It's also customary to present oranges with both hands, and for the recipient to present two oranges when the visitor leaves.