Here is what I find works best:
Find a product that has great reviews, and I would say in the diet niche, quite new, not some old weight loss system that has been around for years.
Decide what the main point of the product is - lets say it is called "Get Rid Of Your Muffin Top in 10 Days" we know it is a diet to get rid of muffin top.
Then use this 5 questions approach to write an article or post. (I got this from a copywriting course here on BHW, I will try to find the link for it - but basically this is the method the woman uses to sell products in a nutshell)
1. What is the problem?
So this is your opening paragraph - identify the problem and expand on it. Say how muffin top is very common in women of a certain age, that is extremely hard to get rid of once it sets in, and how unattractive it is.
2. Why hasn't the problem been solved?
This is your second paragraph. So you would write how most diets target general fat, and nobody has devised a way that focuses specifically on muffin top in the past. And anyway, even if they had, 90% of diets are just too hard to stick to.
3. What is possible?
In your third paragraph you tell them if they were able to get rid of their muffin top, they would look much better, they would be able to wear stylish clothes, and their husbands might even start fancying them again. It would also be less strain on their hearts, they would have more energy, etc, etc.
4. What is different now?
The fourth paragraph will be about how things are different now, because someone has actually devised a way to get rid of ugly muffin top that is not hard to stick to, it doesn't require loads of exercise or expensive items, and it really works.
5. What should they do now?
This last paragraph is your call to action:
i.e. "Click here now to read about how hundreds of Amazon users are reducing their muffin tops with ""Get Rid Of Your Muffin Top in 10 Days".
This is really easy once you get the hang of it. The first four paragraphs only need to be about 75 to 100 words, and in my experience, it is working well with Amazon.