Less is More

"Ever notice how some of your friends look best with no makeup at all? No matter your age, too much makeup makes you look worse. If you wear foundation, powder, blush, liner, mascara, eyeshadow, lip liner and gloss on an everyday basis, then you're overdoing it. Tone it down: All you really need is a great mascara, concealer for blemishes and gloss. Add a pop of blush in winter."

http://beauty.about.com/od/teenbeauty/a/teenbeauty.htm

I personally am against makeup. I'll admit it looks beautiful on some people, but in my opinion it takes away from the natural beauty.
Whether you wear makeup to cover up, enhance, or some other reason, consider this: Occasional makeup for those purposes is fine but wearing it everyday can be bad. In a matter of time, people will have forgotten how you really look. Sure you may be pretty without makeup (most people are) but to people who don't remember, your face will seem naked and you'll appear to be sick when you're not. Be unpredictable--Wear Makeup Today, Be Natural Tomorrow.
Moreover, simple beauty items look nice on a lot of people while for some it looks a mess. I am a highschool student and I see girls everyday trying to wear eyeliner and mascara because their friends do or they think it makes them look prettier. In most cases, they don't know how to apply it and it looks horrible. Mascara and eyeliner are perfect for those who don't wear full makeup, but just to be sure, ask a trusted peer which look do they prefer for you--with or without. In all honesty, makeup is not for everyone. However, if you choose to wear it or not to, just remember to love you yourself <3 and Less is more :)