Best practice for Navigation usability? [closed]

I'm currently working on a social network type system, and was wondering about the best practice for navigation. Would it be better to use Icons or Text? I was thinking a mixture, icons for some things, and text for others. Opinion?

Also, would it be a good idea to implement breadcrumbs?

My target audience is mainly novice computer users, but we are also aiming at computer literate people as well.