You can download the trial version of OmniAudit and look at what triggers
and log tables it creates. Or you could buy it to do the work for you.
Seriously, if you really just want an example, look at generated triggers
from any third party auditing tool. There are a few of them around. There
are things to consider you might not think of such as catching values which
change from null to not null and vice-versa, BLOB columns cannot be handled
the same as other columns because the before values are not available in
standard triggers (unless you go to INSTEAD OF triggers), and so on.
Professional Database Development Tools for MS SQL Server