Set your Instagram to private. Complaints from around the web have been surfacing in of unwanted users commenting on photos with spammy links and unwanted literature.
What are the cons?
For starters, your follower count will not grow as high as you may be accustomed to. With private photos people will be hesitant to follow you because they will only be able to see one picture of you, being your default photo.
What are the pros?
To many to count.
No more unwanted spammy links for one. Only people you know will follow you.
Who wants a bunch of random people following them anyways?