Responding to customer's comments and reactions of our posts on Instagram is underrated. We don't have to do it in prose or convert anything that moves straight away, but doing these little things will make a difference sooner or later. Attention signs matter and impact. Things you can do absolutely for free and that can influence your sales in the medium / long term:
Give it a like, respond with emoticons, react to the comment. It is fast, painless and can bring you joy later. Invest energy in your audience. They will realize.
Show personality and try to maintain a certain tone. That your business is that, a business, does not mean that it has to be like a dull and dry robot.
While showing a certain tone and personality is good, be careful to not show too much personality and take it all to the extreme. Balance is a good thing.
Mention engagers in your comments and responses. Not only will you make them feel that they matter because you pay attention to them, but...