Guessing msn address for someone you don't know address/username exactly

How to guess someones msn address or mail address?

Contact's name may look like:

name.surname@hotmail.com or surnamename@hotmail.com or name."firstletterOfSurname"@hotmail.com
was pretty much used in old days by serious people

if you deal with serious open-minded type that joined "in time of gmail popularity"
(mostly people younger of 30 at time of writing)

nickname@gmail.com

open-minded used also
@yahoo.com @yahoo.co.uk @msn.com seemd rare


someone very simple would use something like
@aol.com or their internet provider domain

if you know where this person work, use domain of company.

Skype search, facebook search, and other will produce more chance to get in touch with this contact.
But if it is about mail password guessing,
then, that's something else..