Most point and shoot cameras have a portrait mode that will often give you pretty good results. But what if you want more control, or if you are using a DSLR without shooting modes? Here’s a few tips, read more at this article on digital photography school
•    Switch to Aperture Priority Mode
•    Choose a Large Aperture for Nice Blurry Backgrounds
•    Select a Low ISO for Smooth Shots
•    Choose the right Focusing Mode
•    Choose the right Metering Mode