For example, if they are standing close to things, they will be more in focus and less blurry. If you have a good amount of distance between them and any background items that will be in the frame of the shot, the background will be more blurry, giving you more of the look you want.
In your photo, I would have your subjects move away from the BBQ grill and the tables in the background, and frame them with the trees most distant as the background. See if you like how that looks. At least with the other stuff out of the picture your subjects will stand out and not have to compete with the visual noise you have in there.