* Look up all CB products inside a particular market, pay attention to their sales letter, look for their reviews on some forums (not your usual webmaster forums, of course). Sales letter is the key here; the gravity doesn't matter.
Try not to choose products that have an insane gravity.
* Look for some keywords (that can possibly convert) in that market and look at the top 5 competing sites, their backlinks, PR and all that stuff. If you figure you can rank, go for that keyword.
Look especially for keywords that have the product name. I rank for numerous keywords like "product name + review/s", "product name by author name", "review of product name", etc. These keywords generally don't have a lot of search traffic but the little that you get converts like anything.
* Put up a site with about 20 odd articles, usually about 600-800 words each, (won't take more than a couple of days), images. You may want to decrease the number but that's the number I usually go for. Works well for me. I've never really paid a lot of attention to on-page optimization so keyword density, etc aren't things I think of.
However, make sure that if you're using a CMS, you're not unintentionally adding duplicate pages, or almost-mirrors. Add a couple of videos and images to your posts. Drip post the posts (over around 60 days, 1 post every 3 days).
* Do some initial backlinks to get the site indexed. After a couple of days, start backlinking. Get links from a variety of sources, use different anchors. You should read up on the new changes and adapt your backlinking to that.
That's that (can be expanded but that's a gist). The key is to choose the right keywords. You can rank — it might take time but you can rank. The worse performers, for me, are sites that are ranking but aren't making any sales because the keywords I chose are not converting/sending me any keywords.