An example of wording a sympathy card is, "My heart goes out to you during your time of sorrow." If you knew the deceased personally, write a message like, "Dorothy was a great source of inspiration to me and will never be forgotten."
If a person's passing is the result of an illness or a long period of suffering, it is appropriate to acknowledge this. For example, say, "John was so strong throughout his entire battle with cancer. I pray that you are comforted knowing he is no longer in pain."
It is also appropriate to offer assistance during this time of mourning. Offer specific ways you would like to help and extend a way for the recipient to accept your offer. For instance, write, "I would be happy to mow your lawn or make you dinner during this stressful time. Please feel free to call me at ..."
Remember that humor is never appropriate when writing a sympathy card. If at all possible, hand-write your note to provide a source of comfort for the grieving survivors of the deceased. Avoid clichés and do not include money with your card unless the loved one's family and friends have specifically asked for it.