Snail mail for sending a hardcopy keepsake cards, little presents or postcards to brighten one's day. Birthday cards works wonders!
Fax when recipient needs hardcopy instantly.
Email. Most preferred mode of correspondance. For information over website. Keeping in touch with friends.
Instant Messaging. Most preferred mode for chatting when skype is not available and phone call is too expensive.
SMS. Most convient way of writing a short & sweet msg. And when phonecall is not convenient.
Phone call. When the answer needed is urgent. To comfort. For, the voice speaks volumes.
Skype when phone call is too expensive!
Off course nothing surpass meeting up and having a drink. The first impression, the eye contact, the tone and voice, the sincerity, the body language and the firm handshake to authenticate the information imparted.