If you want to know how to win back her love, then one of the best things to do is to let her go. Many people hardly accept the fact of losing one's love. It is one of the hardest things to do after breakup. But, if you are really determined on getting back your ex-girlfriend then letting her go is one of the best things to do on how to win back her love.
Things did not turn out well because both of you separated from each other in your relationship. Whatever the reasons are, you should know them in order to come up with better plans in getting her back. There are many people who separated from each other; but they eventually get back to their relationship simply because both of them were able to address the issues that caused their breakups.
In your case, one of the best ways on how to win back her love is to address the problems that caused your separation. In order for a relationship to work better, it requires sacrifice from both parties; such as adjusting to each other's lifestyle and habits. If there are things that you do which your partner doesn't like, then you need to adjust that and change them in order to appease her. These things could smoking in front of her, and she doesn't like the smoke around her; or perhaps she don't like to see you drinking too much alcohol, and so on. In any case, you should talk it over and settle on things to do and not to do in a relationship.
However, in your case right now that both of you have already separated, undertaking a lifestyle change can still help a lot in attracting her back to you even if you are no longer committed to her. For example, if your ex-girlfriend sees that you have already moved on with your life without her, and furthermore you have also stop smoking cigarettes; this will eventually attract her back to you. Hence, in your case, you should the reasons for your breakup in order to make necessary changes that will help you a lot on how to win her love back to you; and these are just one of the most helpful ways in getting your ex-girlfriend back.