Is there a guide out there that explains to the new members the different roles they can play as? What I mean by that is..if you want to focus on X you should look at joining factions like a,b,c. Or if you want to do X here is what you should do..
Sorry if there is something out there and I missed it.
There might be something in The Guide linked at the top of the page. But really its fairly straight forward. You want to produce things, take a look through the various production faction types etc. Prefer to shoot things, the various paramilitary and government groups are your best bet.
There is also the generic skill templates during character creation that can give an idea of what sorts of characters they could be.
Shawn, there might be tidbits written here and there on faction sites and The Guide, as Ellias said. By far your most reliable source would be to speak with someone who has experience in the game, and whom you trust to be impartial, about many of the roles available and how some roles actually work in the Combine. Example: the most common misconception new players have is about the bounty hunter role. That's really just because of which game features are actually implemented at this time and the social dynamics here. Though a brief conversation with a knowledgeable individual can very easily clarify roles such as the one above. I recommend you speak with a knowledgeable friend, if you don't have that then feel free to send me a DM and I'll do my best to help.