Diagonal lines in clothing and accessories can have a slimming affect. The more vertical the diagonal line is the more slimming the affect.
To make your lips look fuller, start by concealing your natural lip line with a concealer. Line your lips just outside your natural lip-line. Smudge the lip-liner onto your lips to soften the look of the liner. Apply the lipstick with a lip brush on your lips and cover the new lip line created with the lip liner. This will create natural fuller looking lips. Using lighter colours and lipstick with a frost or shine will also give your lips a fuller look. If you prefer darker colours add a little spot of a light shimmering colour to the centre of the top and bottom lips. This will add contour and give a more, pouty look.