Ah, Valentine's day. The annual festival of love, romance and chocolate-shaped hearts. The day when things you'd never normally give two hoots about suddenly take on mammoth importance. We all know it's tosh, yet everyone still goes a bit crazy. Those who are otherwise happily single suddenly start feeling out in the cold, while those who were previously happy with their partner can be prompted to question their devotion by nothing more than a service station bouquet.

So, in a concession to Valentine's madness, albeit a small one, today's column is about achieving the perfect Cupid's bow. And it being Valentine's, only red lipstick will do. The science behind finding the perfect red is simple - just match it to your skin tone. So, if your tone is yellow-based, go for warmer reds; if it is blue-black, go for cool blue reds; and if you have a slightly pinker complexion, go for rosy reds. This isn't as complicated as it sounds: basically, the deeper your skin tone, the deeper the red should be.

Once you've chosen your colour, the key to the ideal pout lies in the application. No matter how perfect the colour, red lipstick will never look classy unless properly applied. Don't even think about wearing it without a lip liner underneath. I don't care what you can get away with using other colours. I don't care what you can get away with because your lips are dark. Red lipstick without a liner will bleed and look trashy on everyone, regardless of colour. So go slowly. Match the liner to the lips and keep it sharp. Draw the line inside your lips, and don't be tempted to give yourself a lip job by drawing beyond your natural lip line. It won't work, trust me (this is from someone who spent a large proportion of her school days being told hers weren't "proper black lips": go figure).

Once you've outlined your lips, lightly fill them in. Then apply your lipstick and blot. Repeat, building up the colour slowly; this will not only give it depth but help keep it in place. And there you go, the perfect pout.