The best enhancements are ones that are subtle enough that people you know just can’t put their finger on why you look so great, but noticeable enough to you that it boosts your confidence.
Avoiding “duck lips” is directly related to the injector you choose. Lip enhancement is an art, and going to an experienced injector will be the deciding factor in a natural, subtle look vs. the infamous “duck lips” look. Do your homework, ask questions, and make sure you feel comfortable with the injector and his/her vision for your face.