First thing you do if you're in the US is get an AS # from Arin (
www.arin.net) then you rent a cabinet at a colocation facility, you will want to hire a system/network engineer to initially setup your switches, routers, firewalls and servers, i can do this i've done it for 10 years. Then you decide what it is you want to sell, dedicated, virtual, co-location, both. You then pick at least 2 bandwidth providers who's names arent cogent, then you setup your little network in the colo facility, when you get around 1,000,000 dollars saved up, you build a state of the art datacenter, with a generator, ACs, UPS systems, high tech security and the like.
Thats how I would do it, actually thats how we did it lol.
BMF