The best lip pencil for (almost) everyone because it will match most skin tones, and it goes with most lipstick/gloss colors, is the MAC Spice. It’s been around for a while, but I always come back to it.
I personally feel that most women should use lip liner to bring out the shape of their lips, before applying any lipstick. One of the reasons some glosses and lipsticks don’t look good on a particular person is because a lip liner was needed. Try the difference and see for yourself what a lip liner can do. (The only person who shouldn’t use a lip liner is Angelina Jolie. She doesn’t need it.)
Lip liner gives much needed definition and keeps lipsticks from bleeding. You can also “cheat” a little and go slightly outside the natural lip line, like half-way on the lip and half outside, and make your lips look fuller without looking ridiculous.
MAC Spice is a muted, dusky rose color. It can give a natural look when spread all over the lips by itself.