When a new player first come on, you must do /lookup playername. If the player has more than 2 bans or a reputation lower then 5 do not promote them. Simply let them know that they have to many bans. Do not ban them, just don't give them build rights. Bans such as flymod, bad ban record or stealing do not count towards the 2 bans. If they meet the previously stated requirements you can do the command /setrank player Nomad to give them building perm. Then simply tell them that you promoted them and tell them to read /rules.
If they have even one global ban for greifing, do not promote them.
If they have even one global ban for greifing, do not promote them.