Everyone is right on this one. Dedicated is one of those "if you have to ask you don't need it" things. You have a whole server to yourself but that means you also have the operation of the server such as security software updates & patches, etc. Stats show an unsecured new server coming "on-line" will be hacked in less than 15 minutes if that gives you an idea.

Start with a good shared provider and learn that part of running your site. When you outgrow that you can go to a VPS which is like having your own server but it's just a piece of a big server you are sharing "virtually". With a good VPS provider you will get support to help you through the learning curve then you will know about operating a server about 80% so if/when you outgrow that you will have an idea of how to choose a good dedicated provider that will have what you need...and you will have to have grown to having a HUGE site to need your own server.
Best of luck...but start at the bottom and work your way up. You can have some really big/active sites running on a good shared account.