How to say the right thing on special occasions
Félicitations pour votre mariage
Bonne chance !
Je vous souhaite un joyeux anniversaire
Just as in English, French short set phrases are used to congratulate or encourage someone:
If the occasion calls for a more formal greeting, begin with je vous souhaite ... (I wish you ...). Souhaite is from the regular verb souhaiter.
For particularly solemn occasions like funerals, there's an even more formal way to begin a written message: Veuillez. It really means 'please' and is actually the imperative form of the verb vouloir.