Use hash tags

"Hash tag" is just a fancy word for keyword. You've probably seen them on Twitter and Instagram in the form of a word preceded by the # symbol. When you add hash tags to your photos on Instagram, they become clickable when published, taking your followers to a page of photos that were also filed under that keyword.

The advantage of using hashtags is discoverability. As you make a habit of including hashtags at the end of your captions, you increase your chances of getting followers who aren't your friends. Just be sure not to go crazy with the hashtags--one to three keywords are more than enough.

Tip: You can search for hashtags by going to the profile tab (last tab) and tapping "Search Instagram."