According to CloUdiSm
standard: As a rule of thumb, all problems-related issue are convey
face-to-face. I feel that even phone is not exactly a good thing
(unless I absolutely have no other better alternatives). SMS and
Email are out of questions. Letters is employed when I need a
entire chunk of important message across with 100% 'listening'
attention.
Usually Cancer, Scorpio, Pisces are more vulnerable to my usual way
of speaking. (Water singleton/majority/etc as well. Although
somehow I feel that Gemini, Libra and Aquarius are also affected
when I change my words used).
Body language is very important in communication. You may not
realise this but it send several signal to the mind and if picked
correctly, you may discern certain things you may not know. Body
language is also important - packaged with the verbal side of
communication - it makes your communication effective. Includes
tone, volumn, eye contact, gestures, overall body movement,
sitting/standing position, etc.
P.S: When you communicate, try to do focus more of your weaker
aspect of communication. If you are a speaker, listen more. If you
are a listener, speak more. Of course, always take lead whenever
communication crashes. 
Cheers
