Geotag your Photos
Instagram brings up other photos from the locations that you posted. People are interested in photos from locations that they know. They can post from the same location and might see your pictures and follow them.
Follow and Compliment Popular, Related Users
It is a great way to increase your own base of followers. Try to follow people that follow you. Follow anyone who says they will follow back – they will. Be active on Instagram, make sure to like and leave comments on other people’s photos so they see your profile and may decide to follow you. Try liking random people’s shots. There is a chance that they will follow back. Try liking people that have less than 400 followers. Follow superstars. Follow many people.