Christina sure looks *smokin* in the Tell Me music video with P. Diddy. Below is a breakdown for her look.
Apply a gunmetal eyeshadow (try MAC Knight Divine) over the entire eyelid. Blend a darker color like MAC Black Tied on the crease and extend outwards slightly. Next, highlight the inner corners with a shimmery grey like MAC Electra. Line both upper and lower lash lines with a black pencil and finish the look with tons and tons of mascara.
Cheeks are contoured with a peachy brown color like MAC Sheertone Shimmer Blush in Sunbasque along the cheekbones.
Lips are lined with a slightly darker neutral color (try MAC Spice Lip Liner) and filled in with a pink lipgloss like MAC Prrr Lipglass. Not exactly my kind of look but hell it works for her.