I know nothing about hosting and thought I needed a colo server so I spent $500 for an older underpowered machine. Then I realized I could fit all my accounts on a reseller plan and save money so I shifted down to a reseller and had the server sent back to me. After I outgrew my reseller, I went back up and bought a dedicated server.
A friend of mine started his after he had worked for an existing company for some time, then teamed up with one of the other staff members and branched off.
While he worked there, he had already been working on setting things up for his own business and went straight to a dedicated server, using some of the same providers as his previous company.
He was able to get started quickly, because of all the experience he gained from working with an already establish company, and now he is doing very well.
It really depends on what your current experience may be. Dedicated servers are expensive in money, time and effort, but enable you more control and an oportunity to set yourself apart. If you've very little previous knowledge, then a reseller is definitely a good primer.