Myth is a satin formula which can be slightly drying for some people (it dries out my lips in the winter if I don't let a lip balm soak into my lips before I put on the lipstick. Do you exfoliate your lips at all? I exfoliate once or twice a week with vaseline and sugar. Mix up a little bit of sugar with vaseline (or A&D ointment, which I actually prefer) on the back of your hand, and use a q-tip to gently rub over your lips for about 30 seconds or so, then wipe off with a soft tissue, and apply a good, moisturizing lip balm, gloss, whatever you prefer. I usually use Rosebud's brambleberry rose lipbalm. Your lips should be soft and luscious afterward.
Also, you can try a lip primer to help the lipstick stay on longer...I bought UD's box of potions, and I was really surprised to find out that I ACTUALLY like the lip primer. Make sure your lips aren't dry before you put it on, and don't put on TOO much, but I've found that it honestly helps with the longevity of my lipstick.