At one time, notes were not considered necessary when you thanked someone in person. Today, with guest lists being longer and guests busier, a personal note is the only way to make sure sincere appreciation is expressed. Never, Never, Never, send a preprinted thank you card. When you send a preprinted card, you are telling the person receiving the thank you that their gift didn't mean enough to you to even receive a mention in your note. A warm personalized, handwritten note, regardless how brief, tells the guest how much you appreciated the gift and how it will be cherished for years to come.
Handwritten notes express sincerity.
It is appropriate to thank them for the party or shower in the same card you send thanking them for their gift. When you receive more than one gift from someone, each gift must be recognized with its own thank you card. If you receive a shower gift from a friend or relative and then, three weeks later, receive a wedding gift from the same person, it is not appropriate to thank them in one card. Shower gifts should be acknowledged within ten days of the party and wedding gifts within two weeks after returning from the honeymoon. Wedding gifts arriving in advance of the wedding, should be responded to immediately, so that an extended period of time does not pass between receiving the gift and it's thank you.