Special Days

It is common to use a special greeting used just for that occasion on special days, holidays and other special occasions. Here are some of the most common:

Birthdays

Happy birthday!
Best wishes / Good luck on your thirtieth (age - use an ordinal number) birthday!
Many happy returns!

Wedding / Anniversary

Congratulations!
Best wishes / good luck on your tenth (number - use an ordinal number) anniversary!
Here's to many more happy years together (used when making a toast)

Special Holidays

Happy Ied!

Merry Christmas!
Happy New Year / Easter / Hanukkah / Ramadan etc.
All the best for a happy New Year / Easter / Hanukkah / Ramadan etc.

When making special greetings to children on their birthday and at Christmas, it is also common to ask them what they received:

Happy Ied!
Happy Birthday! What did your Daddy get for you?