Makeup... should I wear it?

I really like playing with makeup at my house and finding all of these cool new looks but I don't know if i'm old enough to wear it, i'm an 8th grader. When my friend was in 5th grade she started to wear TONS of makeup and I may have told her that she was too young to be wearing makeup... so im worried she'll get really mad at me if I start wearing it. Also if I should wear it should i wear just eyeliner or just mascara or do my whole face???