First and most important, so that you don't drown in the topographic ocean, filter the noise by following people (those which give good answers) rather than topics, which will inevitably give you noise. I started by following topics to kickstart my Quora community, but I have dumped most of them now and rely on a peer network for information, which works much better.
The structure of Quora is different from what you're used to. I find the design clunky (particularly on mobile devices), but once I understood the differences between Answers, Comments and Posts it started to become easier. I got this information from the unofficial Quora Etiquette Guide - well worth a read.
Each question is a wiki. Each question (at least the significant ones) attracts its own community. Questions, answers and comments can all be edited, but you can see history of the item (and revert changes) by clicking on the Last Activity link in the left margin. Quora is a multiverse of wikis. It is not a Twitter killer. Got it?
You may be struggling to find relevant content on the site right now. That's because it may not be there (yet). Remember that Quora has had a small user community until its recent explosive growth, and was focused very heavily on social media memes and startups. If you want relevant content, add it to the site and contribute to discussions, e.g: