1. You are too passive. Women respond to men who are aggressive, to men who are predators. Waiting for "the right moment" to ask a woman out is just another way to describe being afraid to pursue. Those who don't chase will seldom catch; stop basing your intersexual relations strategy on science fiction novels written by overweight gamma males.
2. You overrate yourself. If you are an overweight, balding man of average income, or a gangly, pimply student at a state university, neither supermodels nor 8+ women are going to be interested in you. They are elite and you are not. They have much better options than you and Game is not magic. Game will give you two points more range, not five. You don't have standards to be lowered, you have delusions to abandon. If you're an average man, you should pursue an average woman.
3. You are too eager or desperate. Relax. Not having had a wife or girlfriend hasn't killed you yet, so it's not going to kill you in the future. Women like men with options, so don't act as if you don't have any. You do. You always do.
4. You pursue inappropriate women. If you're always trying to save sluts or white knight for women with bad men, you're failing to recognize that those women are right where they want to be. That "poor little innocent me, I'm so unlucky" spiel is something that all of those women tell everyone they come across and it's not real. The fact that she gets cheated on by the thug with the tattooed face is no more surprising than the fact that she won't let you rescue her from him. She doesn't want to be rescued, she just wants an audience.
5. You're holding out for someone better. That's fine, but if you've been holding out for more than five years without finding anyone, you should probably consider the possibility that number two applies.
6. You can't decide. Look, women are like any other aspect of life. You make your choices and you take your chances. A giant green arrow is not going to one day appear from the sky, pointing at the head of a pretty, but shy girl, accompanied by trumpets and a voice declaiming "She, my good man, is The One!" Get advice from men and women you trust, pray about it, consider both head and heart, then roll the dice.
7. You're afraid things might go wrong. It's true, they might. On the other hand, living life by this logic would keep you out of showers and automobiles. Life can be reasonably characterized, if one is inclined towards the pessimistic perspective, as a series of disappointments interrupted occasionally by disasters. But that is true no matter who you are.