Firstly: "Looks" is a result of a genetic raffle. You either got it your you don't--and pretty much completely by random selection. Pretty parents don't necessarily produce pretty children and vice-versa. Also, what is "head-turning" usually is something that is "different"--so no look is inherently ugly or pretty, just normal or unique.
(Proof: why do we like foreign-looking people or mestizas/mestizos? Vice-versa, why do foreigners dig the "plain janes" here?)
Secondly: Using the same premise, compensate for normal looks by being unique in other things. Invest in knowledge, social graces, personality improvement.
Thirdly: But this doesn't mean you can ignore "looks" altogether--because physical appearance is usually the first foot in the door. Make yourself presentable and unique by developing your own style (no need to go with the fashion, but project something unique about you).
Fourth: Tailor your "attractiveness" to the kind of person you want to attract. Don't expect to attract "smart" partners by projecting a "dumb" appearance.
Lastly: Play the game. You can't attract anyone if you don't socialize. In a game of chance, regardless of your inherent odds of success, your likelihood of winning increases only with the number of attempts. You can't win a game you refuse to play.