1 Accept it
In western society at this point in History women are the choosers. They often are rude, hostile or mocking in rejection but some guys cross a line and deserve it. Maybe you didn't, but women are often conditioned to put an advance down HARD so it's understandable. Most women have dealt with unwanted advances before and have developed "policy" answers-(often the same old stock phrases we've all heard too often -especially the "F" word-"friends".) But no one is obligated to be interested so in any event just accept it
2. Accept it with class
Even if she puts you off with unkind behaviors. As long as you've behaved gentlemanly then it make her look bad, not you, and besides, you just got to know her a little better and from what you've just seen would you really want to get involved with her?
Why did she reject you? Had she indicated interest in you at all before she rejected you? Were you rude? Vulgar? Unconfident? Arrogant? Examine your approach including why you thought she might be receptive prior to the approach. The goal is to recognize what errors you may have made and adjust in the future. See Point #
4. It's a numbers game
Women are the buyers and you are the seller. You have to demonstrate value for her to be interested. Women are hypergamous-they date upwards for greater social status and resources. Consider adjusting your approach-including who you approach. Perhaps you overreach.
5. Shrug it off and continue to approach women
You have to be able to do this. Just because you are embarrassed and your ego is bruised don't quit or you will never find a girl. Every interaction is a learning experience. But you have to get back on the horse after you've been thrown or you never learn to ride. Man up-nothing ventured, nothing gained. "Faint heart never fair lady won".
6. Minimize rejection by only approaching girls who have indicated interest
This is linked to point 3-reflection. This is the most difficult part because women like the idea of "plausible deniability" (so as to say you misinterpreted them if you reject THEM. Ironically, women fear rejection worse than men-they are less used to it because it is incumbent upon the man in almost all societies to make the first move). Anyway, the signals they send are tiny-eye contact, a smile, body positions (mirroring), playing with hair, etc. Without any of these indicators your chance of rejection rises and even with them if she doesn't like your approach or conversation she can deny she was interested.
7. There Might Be Other Reasons
Many women send indicators of interest either consciously or unconsciously without intent to follow through for other reasons. She might be attracted but not accept for other reasons. She may be married, in a complicated relationship, from somewhere else or any one of ten thousand things.