It's often useful to re-emphasize your board policies now and then. 99% of your users probably won't read the board rules when they register.
A good way to keep members in line is to provide a link to your rules in a visible location.
Once you define your board rules then it is up to you and your fellow admins and mod staff to tow the line. Be consistant and fair in your dealings with members, and they will usually abide by the board culture.
Banning should typically be reserve to try to keep out the baddies and those whose only purpose is to spoil the fun for everyone else, but even that doesn't always work if they are determined enough.
Always try to resolve the conflict with the user privately. Use a PM to contact them and explain the problem...calling them out in the public forums will only embarrass them and foster resentment.
Removing posting privs and locking profiles can be an effective tool, but with most administrative decisions you should take the extra step to inform them, lest they re-register and post "why am i banned".
