The most common way to begin a sympathy card note is to start with the word "Dear." You could also write "Dearest," or simply start with the person's name. Avoid starting with "Hi" or another casual salutation - err on the side of being a little formal.  Address the person to whom you're writing as you'd normally address that person. If you're writing to a teacher you normally call "Ms. Frankel," address her that way in the card. If you're writing to someone you know well, using the person's first name is appropriate. If the card is meant to express sympathy to an entire family, and not just one person, write each person's name out. If you don't know the names of everyone in the family, you could write "Sarah and family." Say how sorry you are to hear that the deceased has passed away, and if you knew the person, mention his or her name. If you didn't know the person, you can refer to him or her as "your mother" or "your grandfather," and so on. For example:  I am so sorry that Miles has passed away after his long battle with cancer. I am deeply grieved to hear of Margaret's passing. Words can't express how sorry I am that June is gone. Ending your note after briefly expressing sympathy is perfectly acceptable for a note you're sending to someone you don't know very well. Include a phrase that is conventional and has no chance of being misconstrued. Choose to write something like "thinking of you in sympathy" or "please accept my condolences" if you wish to keep the note on the short side. This is especially appropriate if the sympathy card you're using already has a printed poem or note inside. Examples of other appropriate brief sentiments include:  You are in my thoughts. Our thoughts and prayers are with you. We are thinking of you. I'm praying for you during this difficult time. We will honor the memory of [deceased] during this time of sorrow. [Deceased] will always be in our thoughts. If you knew the person who passed away, write how much you will miss him or her, and share a few things you remember. Demonstrating a shared grief will make the recipient of the card feel less lonely during his or her time of loss. Briefly mention something special about the person, or how much that person meant to you. Writing a few words that invite the person to call you or reach out to you if you are needed will probably be welcome. Be sure you're ready to follow up on it if the person indeed reaches out for help. If you know the person well, you may simply want to write "Love," then sign your name. If you're sending a card to someone for whom that closing wouldn't be right, choose a closing that best expresses your feelings and your relationship to the person. For example:  With caring thoughts, With loving memories, With love, With deepest sympathy, With heartfelt condolences, Our sincere sympathy,

Summary:
Start with an appropriate salutation. Write how sorry you are about the person's passing. If you don't know the person well, consider keeping it brief. If you know the deceased, consider sharing memories. Offer help or assistance if you'd like. End your note with an appropriate closing.