I run review sites in many markets such as gaming, travel, entertainment, shopping etc. My advice to you would be to not focus on just reviews. Bulk the site up with other features such as news, comparisons etc.
I earn my commissions through various monetizing strategies such as adsense, affiliate banners. However the content my sites provide is not mine. It is all provided by content partnerships and API'S.
For example reviews on my many sites come from content partnerships such as CNET, Amazon and Epionions. You can also use content feeds such as Google News and API's such as Kelkoo and Shopping.com. Although it all depends on what niche you are based in or what you are trying to promote.
These are the methods I use. However these are the methods I use for building my brand website portals. These are no just throw away websites and I would not suggest using Black Hat methods or traffic on them. Mine are White Hat based.
I do have Black Hat review sites but these are of a different strategy. For these I just have a landing page review style website with a few products on reviewed. I find these the best types when using Black Hat methods to promote.