I'm NW 45 to 50 depending on the foundation.
For a nude lip, I either start with a concealer, then blot and apply my lipstick/lipgloss.
Or better yet, I like to line or fill my lips with cork (or chestnut for a deep chocolate look), then apply any brown shades I wish.
I'm not giving specific names of lipsticks/lipglosses I use because I don't have any faves really. My "nude" changes depending on what I want it to look like. Because I'm a deep chocolate color, "nude" for me is really a dark brown, but sometimes I may want that fleshy, beige shade for a traditional nude lip. I've used every color of lipglass from Jazzed Cremesheen (light pale orange) to Shock-o-late lipglass (dark brown), it just depends on the kind of "nude" I'm going for.
So, I find the key to the best "nude" lips for me is heavily reliant on the lipliner (or concealer) first. I know how to use lipliner to my advantage so now, I can use many of the shades I used to think were "ashy" before and still get a beautiful effect.
(Side, yesterday, I filled my lips with Chestnut liner and used a touch of Beaux lipglass on top... it was *the* sexiest chocolate lip I've ever had. Totally loved it and can't wait to wear it again.)