The first thing you should consider when creating your blog is to provide an honest review of the product that you intend to sell.
Mentioning the downsides of a product (not to the point of bringing it down) will make your site more believable.
You may cite at least one or two minor not-so-good reviews.
Blogging with 100% positive surveys may be tagged as fake.
Of course, you may give an honest review by personally evaluating that product that you are selling.
I suggest that you must positively blog your product while assessing if such review will ruin your reputation.
The second secret to increase your sales through blogging is you should stand out from the crowd.
Since this type of marketing strategy is popular and being used by many large, small and solo entrepreneurs these days, there's a huge probability that they are already offering the products that you plan to sell.
The point here is you may start offering something that other sites do not provide.
Aside from writing posts, what other things you can offer? You may opt to make your landing page appear different and more appealing compared to others.
Although customers have seen the same things repeatedly from other sites, their attention can still be caught if you have a different and not too common page.
Lastly, you should build a relationship with your readers and followers.
The whole idea of blogging is to provide good content and information to your clients and prospects.
By doing this, you will earn their trust thus giving you a convincing power over them.
You may not notice it but you will find that each time you promote a product via blogging you are making few more sales.