Instagram is a great platform to advertise if you follow other businesses and accounts that have similar focus as the topic of products or services you are promoting on your Instagram. This encourages audiences of the same interest to follow your account, and you may gain loyal customers who are already fans of the product or service you are offering. There is also a promotion section of Instagram business that will advertise your post (also called promoted posts) for a fee. This gets your post onto other people's feed.
I would also suggest linking your online website to your account, which can be displayed on your main page. It is best to have a business account, which can be set up once you create a normal Instagram account. It is an option under settings. This provides you with insights for how well your posts are doing, and it also puts a button on your main profile page that customers can email you through.
Have contests or giveaways. This not only rewards loyal followers, but if you set it up where the contest participants have to re-post the giveaway post and share it with a certain hashtag or tagging the company's username, you might be able to spread your reach and get more people interested in what you are selling. Amazon has a useful giveaway program. Entice people to enter your giveaways or contests. It will draw in people who may find themselves to want to purchase your product or service for themselves in the end.