Nude lips are very natural looking and can be very sexy if you choose the right shade for your skin tone. If you choose a shade that is to pale it can make you look dead or seriously ill!!
You can either choose a lip gloss such as MAC underage or wear a lipstick with a slick of clear lip gloss over the top.
If you are feeling flush I really like NARS Belle de jour. It is a deeper nude than the other two lipsticks but looks really great with a clear gloss over the top or a very light pink. NARS Lipsticks cost £17 each which is a bit on the steep side but it is a good product and you only get what you pay for.
MAC do a gorgeous lipstick called Myth which is alot paler than the NARS Belle de jour but would look fantastic with a tanned skinned and a bronzy look. Slick some clear lip gloss over the top and you are good to go! MAC's lipsticks are £11 each.
If you don't want to spend alot of money on a nude lipstick then Barry M do a gorgeous browny-pink lipstick that goes on very soft and smooth. It is a steal at only £4.25 and has everything you would expect from a lipstick really! The shade is a little darker than MAC myth because there is brown in it as well as pink but it is still a really pretty colour.