http://www.uni-regensburg.de/Fakultaeten/phil_Fak_II/Psychologie/Psy_II/beautycheck/english/prototypen/prototypen.htm
The research on this site explains a lot of what qualities makes a face attractive.
What makes a male good looking besides mentioned in that site like facial symmetry, porportions etc, is really just the absence of things that are unattractive.
Attractive:
symmetrical and proportionate face
Good hair
Good and aesthetic teeth
Good skin complexion and condition (slightly darker complexion)
Height
Leaness
V-shaped (broad shoulder/slim waisst)
Youthfullness/healthy
Unattractive:
Blading/thinning hair
Bad teeth or just not aesthetic
Wrinkled, blemished, pale skin
shortness
Fat
slender shoulders
Aged/unhealthy
You're 18 so you should naturally and easily have good skin, hair, leaness, youth and healthiness. As you can imagine most of these things are not really fixable if lacking.