Most of the most popular stock photos have people in them. You must have a model release for all identifiable people in your photos, unless you take an editorial photo. I by identifiable they pretty much mean that if there is a person they must have signed a model release…
You can find sample model and property releases in Shutterstock’s legal page. The trick is then getting people to sign them. Start with family and friends who are willing to be your models. My sister is game for any photos. With my sons I tend to angle the shot so their faces aren’t exposed as much, keeping in mind their photos could end up on the side of buses or on billboards. I have approached some strangers to see if they would be willing to have their photos taken, such as this cute dancing couple, and so far they have all signed, but it’s just not something I’m very comfortable with, likely one reason I have focused more on editorial.
But many people are quite comfortable doing so and are very successful, so don’t let my hesitation stop you!