Keep it simple. You could start with a lip gloss or a lip stain in shades like peach, baby pink or nude. Avoid lipstick and stay away from dark lip colors as they don't suit youngsters.
The key is to look fresh and pretty, so don't overdo your eyes either. Use an eyelash curler to give shape to your lashes, then apply a coat of mascara. This will give your face a fresh, open eyed look. Your eyes don't need anything else, but if you're going for a wedding, you could apply a little bit of kajal to define your eyes. Ensure not to use heavy, dark eye make-up as it would only make you look older. Eyeshadow is also not recommended as it could look a bit much.
Your skin at this age doesn't require any foundation, but if you must, you can go for some blusher. Don't use powder blush - choose a cream blush in a subtle shade and apply on your cheekbones to add a rosy glow to your face. Make sure not to use too much, and blend it well.