Both of these techniques work because the cuticle scales are pushed apart and tangle with each other.  Both methods give lift and volume to the hairstyles.

Hold the points of the ends of the hair firmly in one hand and either back comb underneath or back brush on top then gently smooth over the top to give a neat finish.
Always stand some distance away from your client to check the finished result, especially shape. Look for any break or gaps in the dressing and smooth over if necessary.

Check the overall shape, looking at the back, sides and front. Does it frame the face properly? Remember that the client only sees the front area. It is the most important part of the dressing.

Hairspray may now be used to finish and hold the shape.