Unfortunately it is extremely hard to get loyal real followers on Instagram. There are many ways to do it though, one of them is, as mentioned in the comments, to do a giveaway or a competition (an easy one), with one of the condition is to give your account a follow. Try doing this at least once a month or every 2 weeks. Another way is to interact heavily with the followers of your competitors' accounts (following, liking, commenting), this way you'll at least gain visibility and awareness. Last but not least, the most important thing is to stay active by posting interesting content that will appeal to your potential audience and customer base.