How do I get our emails to land in subscribers' inboxes?

Hello! 

My name is Ashley and I am the media manager for a dance studio. We use constant contact to advertise as well as update our dance students on things happening in our studio. Lately, people have not been getting the emails we have been sending and when I tested it on myself it was going directly into my promotions folder instead of the main inbox. Is there a reason for that? Is there a setting that is tagging it as a promotion? And how do I get the emails to send directly to the main inbox. 

Thanks for any information!

Ashley