I thought about the best way to answer this question, and decided that a good place to start would be to list the websites that I have frequented over the years, with reasons why I started reading them, and reasons why I stopped:
Bluesnews: This was in some ways like an early RSS feed, but with good editorial. It brought a lot of things together in one place, from standard 'news' about upcoming games, to community news (it was heavily Quake oriented), to .plan (oldschool blogs, basically) updates from developers, to some great articles about benchmark performance, guides to different games etc. I stopped reading it because it got to mainstream and my interest in mainstream gaming was waning.
Firingsquad: I started reading this because it was founded by one of the original 'progamers', Thresh. It had some great editorial content, such as the early "Face Off" articles where different writers would argue the toss over a given issue. It evolved over the years into something of a hardware site, but with heavy gaming focus, which was what I was looking for. So I could I go there, and not only read game reviews, but also see benchmarks for the latest and greatest cpus, graphics cards etc. I stopped reading it because it stopped being updated frequently - it would no longer be posting articles the moment the NDA lifted. To be fair I was a fairly frequent visitor for about 10 years, which (google and ocuk forums aside) probably makes it the longest serving website I have.
XSReality (later became ESReality): Kinda like the above, this was founded by a couple of legendary Quake players (Sujoy and Xenon). Had more of a hardcore focus, very in depth hardware reviews from a gamer perspective (the sort of detail you couldn't find on mainstream sites). Stopped reading because the focus shifted towards modern games that I wasn't really interested in.
IGN: At one stage (around 10 years ago) this was quite a good site as it had a good range of content about games, and was my 'go to' site for game reviews. Stopped reading as their integrity started to come under scrutiny, and the focus was shifting more towards consoles.
This is of course ignoring any game-specific websites like quakeworld.nu.
Anyway, so the next step is to actually answer your question! I think to make me a regular visitor, rather than just following google links, the following would be appealing to me:
-Writers that I respect making frequent updates of a reasonable size (at least 3-4 times per month - not regurgitated news but original editorial content)
-High-quality, vetted bloggers (i.e. not just a soapbox where people can spew whatever they want - not that I don't think there is a place for such things...)
-Age-agnostic i.e. not purely focussing on the latest/future release but also writing about games that came out last month, last year, last decade.
-Game walkthroughs - I find these useful. I quite like the
www.visualwalkthroughs.com site, even though it is very dated - the concept is sound and is writing in a good, simple style highlighting key points rather than the "trying to sound cool" style that many adopt in walkthroughs.
-Simple homepage that isn't in my face with auto-playing videos and pictures of female editors.
-Easy way to identify new content, whether it be blogs, news, articles, forum posts etc
-Some sort of 'hardcore' stance. Now I don't mean walls of text using acroynms and phrases nobody understands unless they've played game XYZ for 5 years, but just a general attitude that takes certain things VERY seriously and goes overboard with the level of detail and depth of analysis. The type of stuff you simply wouldn't find on the mainstream sites. The type of article that might have over a thousand words just talking about tactics for using a single weapon/unit rather than 500 words about tactics for an entire game.
Overall, my advice for any new gaming site is do not simply become yet another site posting news, reviews, videos etc. Other people will have far more resources and existing readership base. Get yourself some kind of USP, find a niche in the market (sometimes this may mean focussing on a particular game, or genre), go extremely in depth into one particular facet of gaming (hardware, configuration... whatever!) - do something original.