Hi Iwan,

The basic reqirements you will need are:

The most important one is customers or at least an advertising plan to get the customers.

A business plan is the 2nd most important but I'm not going to tell you how to do that hear theres not enough space.

A domain name, one that is easy to remember and although not necessary, if possible it should be relavent to your business (the hosting industry).

A parent hosting company to supply you with the reseller packages.

A basic understanding of web hosting.

And a payment system, one where you can except credit card and online check payments through. Some suggestions are 2checkout, paypal, clickbank, authorizenet and worldpay, these are just a few there are literaly hundreds to choose from.

Thats the basic needs to start as a reseller but there are a lot more things to consider as you progress like other features to add to your business etc.