There are two way's of expressing gratitude for your guests thoughtfulness. First, every gift should be acknowledged. It doesn't matter if they were, money, gift of time, talent or a tangible item. They should be acknowledged in writing. Most of all the acknowledgement should be done promptly.
Personal, handwritten thank-yous remain the standard of courtesy, even in the age of smart phones, IPad, instant messages and computers. Hand written notes demonstrate that you care enough about the giver to compose an individualized message and put words on paper.
How to say thank you:
Respond in a timely fashion (Your thank-you notes should be written and sent within three months)
Share responsibility (Bride and Groom working together as a team.This make it easier to tailor notes to individual givers)
Include your fiance/fiancee or new spouse in the thanks. (Your messages of gratitude should be expressed from you both.)
Don't take shortcuts (It is Not ok to use a pre-printed card. Simply signing a store bought card shows very little consideration.
Think about it this way, what kind of thank you would you want someone to send to you.