No matter where you go, there will always be people who will try to get more than they pay for. This is certainly true for web page hosting industry as well. These people will bog your server down with things such as torrent clients or even media streaming and will threaten to go as far as suing for a lousy $5 or $10 product.
You should have a AUP or Acceptable Usage Policy defined with what you allow on your servers and what you don’t. You should also have a Terms of Service page defined with the industry standard notes and if you have anything special to add, this is the place to add it.
Define your termination, cancellation and refund policies sharply. Don’t beat around the bush and state it just as it is. This is one of the primary causes of a dispute between you and your customer and youfll save a lot of effort just by doing that.