the corners of my mouth naturally turn down. I look bitchy or sad when its just my regular expressionless face.lol How can I apply lipstick to make this less noticeable. I have to be careful as I have full lips so if I colour outside the lines I can look like a clown.

Well if you can buy different kinds of tips for your lipsticks (slanted, rounded, triangular, etc.) when can make it easier to use. If you're really having trouble applying it, then take a make-up brush and use it to fill in any missing spots.