You will need to spend some time removing dead skin. With a soft dry toothbrush, you can effectively remove dead skin . Do this at least once a week.
Use lip balm to moisturize your lips, and to prevent dry lips. But avoid flavored lip balms, because they make you constantly lick your lips, and thus cause lip chapping.
If you want your lips to look larger, on the lower lip center, apply a little lip gloss. The gloss will reflect light, making the lips look larger.
If you have thinner lips, avoid darker lipsticks. They will highlight your thin lips. Try to use neutral color lipsticks.