A while back I asked a question on GAG titled what should I do to get a girlfriend?. At the time I didn't have my priorities set straight and didn't fully comprehend the truth behind the person's answer.
The points outlined below were in his response and I figured I would expand on them. These points apply to both males and females.
Make sure you really understand what you want
A lot of people both on GAG and in the real world want a relationship but when asked what this relationship will include often cannot come up with a proper response. People often see relationships as a way of becoming happy.
If it is happiness you seek then you must clearly define what happiness is. What makes you happy? What do you enjoy? Introspection is a very important first step and that is why I strongly recommend that you read Managing Oneself by Peter F. Drucker.
Know what your strengths and weaknesses are
Peter F. Drucker in his article points out the importance of focusing on your strengths and avoiding your weaknesses.
One should waste as little effort as possible on improving areas of low competence. It takes far more energy and work to improve from incompetence to mediocrity than it takes to improve from first-rate performance to excellence.
Improve on what you're good at and find out what positive qualities you have. Try to avoid your weaknesses and you'll see that you will be more successful in life.
Accept yourself and Don't change for anyone
If you can't accept yourself how do you expect others to do it? You are you, not someone else and you have to live with it. If there's something about yourself you don't like then fix it. If you're too fat, go to the gym; if you're too skinny, eat something; but most importantly don't go overboard. There's a limit to how much you can do and you're just going to have to accept it, there's no other way. Don't change your personality for anyone. If that person doesn't like you then they are not meant for you. I know it's a tough pill to swallow but it's true. Otherwise you'd have to pretend to be something you're not, just to be in a relationship.
Make friends with people of the opposite sex
By hanging out only with people of your sex you miss out on an opportunity to learn about how the other half thinks. At times you might even notice that people of the opposite sex can make better friends because of the dynamic that is present between you. For example, some girls prefer to have guy friends since they don't care about fashion and aren't always trying to one up each other.
Become Financially Independent
Every single person should strive to become financially independent. Your partner is not your piggy bank and he/she shouldn't have to pay for your dinner just because you are too cheap. Financial independence also allows you to purchase goods and services that you may be interested in outside of a relationship. By being financially independent you gain a sense of security and greater self worth then a person living of welfare or in their parent's basement.
Lastly, become busy
Find a purpose for yourself since sitting around wallowing in self pity isn't going to change anything. Find a job or a hobby and give it your all. Elliot Hulse explains this concept very well. It applies to both men and women even though he is only refering to men in this video.