Hi Andy,
the wiki is your friedn ;)
Have a look at
http://adempiere.com/index.php/Table_Prefix
Besides what is recommended there for your own prefix I would recommend
to create your own entity type(s) with a three or four letter
abbreviation and use that as table prefix (and for the type for that
table and its columns and so on of course).
Regards,
Dirk Niemeyer