First you need decent software, if you have Photoshop you should be good, if not download this program
http://www.gimp.org/ , it's a free Photoshop pretty much. Then you'll need fonts, brushes, and renders (AKA, resources) to use. As for the brushes and even a tutorial go to,
http://www.deviantart.com/ . As for fonts,
http://www.dafonts.com/ , for renders use
http://www.planetrenders.net . You can C4Ds from PlanetRenders and DeviantArt. At DeviantArt, search for a tutorial, you'll need it. If you do use GIMP go to
www.gimptalk.com for a bunch of good tutorials. Hope that helped. If you need more, I can give you a few GIMP tips.