Keep it simple and sincere: "I just heard you got engaged. That's wonderful. Congratulations! " Then follow up with a basic question, such as, "When is the wedding? " Try to sound genuinely happy and interested. A handshake or hug is appropriate, too, depending on your relationship with the other person.
Sincerely expressing, "Congratulations on your good fortune, addition, or good news. ", in person, on a card, or by giving a small, thoughtful gift is always appreciated. Wish them the best!
Usually you try to keep it fairly simply. "Congratualtions on your engagement! I'm so happy for you! You guys are perfect for eachother!" or "Congratulations on your new baby! He/she really is beautiful." or "Welcome to motherhood/fatherhood. You'll be a great parent!"
The first important aspect it to state the fact of the happening and then proceed to express how fitting it is. By this time you have broken the ice and it gets the more easier to say it.
Offer them an enthusiastic and warm, "Congratulations! " Offer to help any way you can, but only if you will follow through. Then ask them about the event.
