Ferguson identified four different types of facial expressions on the front cover of British women magazines.
This would be what is known as the Chocolate Box. This pose consists of a half smile, lips together or slightly parted so the teeth are barely visible and lastly a full or three quarters of the face to the camera. Overall generally a sweet pose, hence the name. The effect that is created from this expression is uniqueness and also an uniformity of beauty.
This is what is called the Invitational pose. The main focus is the emphasis on the eyes, which looks inviting. The mouth has to be shut with a small hint of a smile. The head is either to one side, or looking back over the shoulder at the camera, as you can see from the example. The effect created from this pose is the suggestion of mischieve and rather than a sexual promise, it's more a hint of contact.
The Super-smiler. This pose has to contain a full face which contains a wide open and toothy smile. The head can either be thrusted forward, or the chin can be thrown back slightly. The hair in the photo often looks softley wind blown. The effect created by this facial expression and body language is a slightly aggressive and 'look at me' attitude.
This is known as the Romantic or Sexual pose. It includes a male or a female, often two-somes. The photo itself needs to be dreamy, sensual and sexual. The model tends to be heavy lidded to create this effect. The main effect created by that the person in the photo is presenting themself as 'available'.