Letters of condolence should be just consise Some. The main thing is that the words were sincere, without unnecessary pathos. This letter should be sent immediately after receipt of notification of death. It is not necessary to send a letter of condolences after a considerable time to once again not to plunge into mourning people, perhaps, to some extent already resigned to the loss of a loved one.
A letter of condolence be made on plain white paper and sign in person.