I'm sure you'll get a ton of answers and tips from IG gurus and influencers here, but before you start creating your content, think of easier and more authentic approach. What I mean is using your customer photo reviews in your remarketing ads. It's actually very easy: of you're using any app for reviews, you can use these customer photos and put them in you Dynamic Product Ads that work on Facebook and Instagram.
That kind of ads follow your site visitors on FB and IG, targeting them with reviews of the exact products they were viewing at your store. You can't get more relevant that that ;)
Not many stores are doing that yet but it proves to be super effective, as people tend to trust user-generated content more that the most sophisticated ads.
I've written a case study on that, will be happy to share it with you:
IG is a beautiful tool for marketing, but you really have to put a lot of time, effort and thought into it, and it still may look like all the ads out there. Try to stay natural and close to your customers.
All the best with your business!