Reviews and product testing in general, or specifically woodworking?
i would think that for starters, you will have to do some work for nothing (probably quite a bit), to enable manufacturers/editors to see your work, and to get yourself known. Thereafter, you may struggle to get paid for a lot of it- instead you get to keep the product, or may get paid for a magazine article on it. I imagine that there are a lot of people willing to help out the manufacturers with product development, perhaps for no formal reward, other than the odd tool that need not be returned. There is prestige in being asked by the manufacturers for an informed opinion on their latest offering, that payment is just not necessary- in the same way that we share knowledge on the forum with design ideas, and WIP's.
Derek Cohen's "in the woodshop" and Alf's "Cornish workshop" will give you some ideas of some good product reviews.
I dont want to rain on your parade, but I think you need to know from the start that you are going to struggle to earn a lot from it. However, to start up, there are sites like this forum where reviews are welcomed, and blogs are cheap to get up and running. It need not be the latest offerings from Veritas vs Lie Nielsen that is reviewed, which would cost a lot to buy just for the sake of reviewing- a blog entry on cheap car boot block planes, for instance, would be interesting, or plane fettling, or any one of a number of different articles.
HTH
Mark
