Funny you say that, over the last 18-months I've been writing articles for an Australian detailing supplier, helping flesh out the blog/buyers guide section of their webstore. It's actually been a huge confidence boost for me personally, while being able to have a (very small) part in the industry and being privy to some insider info, for example I knew the ADS brand was coming months before it went on sale, same for Labocosmetica.
It's a very different style of writing, instead of my usual longform style here, I need to be mindful of being concise and integrating product links. It's all about hitting keywords to maximize search results and speaking to a much wider customer base. Put it this way, I need to refrain from using typical detailing lexicon, instead being more general so as to not alienate the novice.
In terms of being paid for this service, I was given a couple of options, including free product. Personally, I chose to be paid per article, I think that is the best way to remain somewhat independent and impartial. I then have control over what I review or write about, meaning I'm not writing about products I don't believe in. For example, being the Australian distributor for ADS, I've written extensively about the brand because I like and believe in the products, of which I bought every one of them with my own money.
At one point, I was sent the entire Bilt Hamber product lineup with the intent of doing a range review. Some of those products I would have naturally bought, some of them I would have chosen another brand instead. But because it was all free, naturally there is pressure to perform favorably for the brand and company I'm working for. I didn't like that. So instead, I focused on delivering an article that properly explained what each product does and is used for, because I don't know about others, but I find the Bilt Hamber product descriptions to be very ambiguous. So, my article provided value by making the products more approachable.