You will need

- some serious money: servers and software are not cheap, and clients expect solid webhosting that you can only provide by buying reliable products

- familiarity with software and various platforms

- time especially since clients want 24/7 support (so you need to have staffers as well)

Here are some websites and web documents on how to start a web hosting business. These websites give you information on how to set up your own web hosting business:

HostingResolve.com's Starting a Web Hosting Business http://www.hostingresolve.com/book/ch01....

Becoming a Web Host Company http://www.dedicated-servers-seek.com/?a...

HostLibrary.com's Starting a Web Hosting Business http://www.hostlibrary.com/node/print/65

Another way of course is to simply become a reseller of a web hosting company, which is easier to start. Many hosting companies offer private label programs where you use their infrastructure but you can brand the business with your company name. An example of how this goes is Hostway's Private Label program http://www.hostway.com/resellers/private...