Hello, you didnt mention about your product which you are selling on AMZ. But let me give you idea how I managed to lower down ACoS from 41.88% to 23.65% for one of my clients whose product was also in the same niche. Since I don't know your product, I'll explain my strategy in general.
AMZ allows 3 types of advertising:
Products Ads (Advertising on AMZ main page, i.e., top position, bottom position)
Brands Ads(You advertise your list of products on AMZ Main Page, i.e., Top position only)
Display Ads (Advertising on product display page, i.e., below add to cart button, product bullet points and product description)
After running both of these campaigns in sponsored product and sponsored display ads, using super relevant kws, I was able to get a higher no. of impressions which helped in greater conversions. When there are new ad placements, you may see an increase in impressions, clicks, and sales. By continuously keeping in check all the above measures, I was able to achieve greater sales while reducing ACoS to 23.65% just in 1 month.
But before starting, you need to have a highly optimized listing with proper kw placements which aids in kw indexing. If your listing is not optimized, your PPC campaigns won't work. So, I usually audit my client’s listings to achieve greater sales.
Well, this is a simplified version of my strategy just to give you an idea.
I’d like to respect your time and keep it short for now.
Just for curiosity, what are you selling on AMZ?
Cheers!