Round
To add more definition to a round face, trace the  entire perimeter (outline) of your face with the contour tone. This includes the hair line, down to the jawline and all the way to under the chin.The most common place and easiest step to contour is by adding definition to your cheekbones. Draw a line starting from the start of your ear (where sideburns start). Next, just add a little to your crease and you are ready to highlight.
Dab some highlighter just above the center of your brow, a line down the center of your nose, the apples of your cheeks, your entire eyelid and under your brow and blend.

Oval
To even out an oval face, highlight the outside of the jaw instead of contouring it. Since it is already narrow we want to bring it out. Contour the outside of the forehead to balance it out with your jawline by making it look more narrow. Focus on placing highlight more in the middle of your face like around the nostrils and between the brows and above the cupids bow.

Heart

For a heart-shaped face we want to make the jawline wider and the forehead smaller. Start by contouring the temples, under the cheeks, along the crease (eyes) and top of the nostril. Highlight the center of the forehead, apples of the cheeks, the chin, under the brow and just the top of the jawline below your ears.

Square

Having a square face is almost like you were born with contouring lines. If you want to soften the edges, contour the jawline and under the cheeks to show off those cheekbones. Highlight the center of the forehead, move down the center, edge of the nostril and around the edges of the lips to draw attention onto the  middle of your face rather than your strong jawline.

Tip: Your nose shape is entirely different from your face shape, so if you do have a wide nose go ahead and contour. Remember only to contour when needed. For example, my nose is slim and contouring it actually makes it look longer and bigger. I had to learn that the hard way through photographs. Keep in mind this is to accentuate the beauty you already have so only follow this trend on areas your really feel you need it!