I Want to Sell Web Space

I am having a dedicated server and am thinking of reselling server space. However, I am not a pro on managing server and was wondering if some of the experts over here would be able to help me out? 1) Is there any specific thing that I need to keep in mind or need to be carefull of before I start selling web space. 2) Is there any real danger or possibility that someone (customer) can harm / hack other accounts on the same server ? 3) Is it ok to give SSH or should I be carefull to whom I give SSH? Thanks for all the help.